diff --git a/Cargo.lock b/Cargo.lock
index 6d05c54..4f945ac 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -157,7 +157,7 @@ checksum = "13dc2df351e3202783a1fe0d44375f7295ffb4049267b0f3018346dc122a1d94"
 
 [[package]]
 name = "marisa-rs"
-version = "0.1.0"
+version = "0.1.1"
 dependencies = [
  "bindgen",
  "cc",
diff --git a/Cargo.toml b/Cargo.toml
index 833fc91..ea69eba 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "marisa-rs"
-version = "0.1.0"
+version = "0.1.1"
 edition = "2021"
 description = "Safe Rust wrapper for the marisa-trie C++ library"
 license = "LGPL-2.1-or-later"
diff --git a/README.md b/README.md
index b9ace87..f2065fa 100644
--- a/README.md
+++ b/README.md
@@ -57,11 +57,39 @@ keyset.push("car");
 keyset.push("card");
 keyset.push("care");
 
-// Build the trie
+// Build the trie  
 let mut trie = Trie::new();
 trie.build(&mut keyset)?;
 ```
 
+### Saving and Loading Tries
+
+```rust
+use marisa_rs::{Keyset, Trie};
+
+// Build a trie
+let mut keyset = Keyset::new();
+keyset.push("hello");
+keyset.push("world");
+
+let mut trie = Trie::new();
+trie.build(&mut keyset)?;
+
+// Save the trie to a file
+trie.save("my_trie.marisa")?;
+
+// Load the trie from a file
+let mut loaded_trie = Trie::new();
+loaded_trie.load("my_trie.marisa")?;
+
+// Or use memory mapping for better performance with large tries
+let mut mmapped_trie = Trie::new();
+mmapped_trie.mmap("my_trie.marisa")?;
+
+// Check the serialized size before saving
+println!("Trie size: {} bytes", trie.io_size());
+```
+
 ### Lookup Operations
 
 ```rust
@@ -128,6 +156,11 @@ trie.build(&mut keyset)?;
 - `trie.predictive_search(query, callback)` - Find all keys that start with query
 - `trie.size()` - Get the number of keys in the trie
 - `trie.is_empty()` - Check if the trie is empty
+- `trie.save(path)` - Save the trie to a file (returns `Result<(), &str>`)
+- `trie.load(path)` - Load a trie from a file (returns `Result<(), &str>`)
+- `trie.mmap(path)` - Memory-map a trie file for efficient read-only access (returns `Result<(), &str>`)
+- `trie.io_size()` - Get the serialized size of the trie in bytes
+- `trie.clear()` - Clear the trie, removing all keys (returns `Result<(), &str>`)
 
 ## Japanese Text Example
 
diff --git a/src/lib.rs b/src/lib.rs
index 4b1a656..24bc247 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -29,6 +29,8 @@
 //! ```
 
 use std::slice;
+use std::path::Path;
+use std::ffi::CString;
 
 mod bindings {
     include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
@@ -198,13 +200,124 @@ impl Trie {
 
     /// Returns the number of keys stored in the trie.
     pub fn size(&self) -> usize {
-        unsafe { marisa_trie_size(self.inner) }
+        unsafe {
+            let mut size: usize = 0;
+            if marisa_trie_size(self.inner, &mut size) == 1 {
+                size
+            } else {
+                0 // Return 0 if there's an error
+            }
+        }
     }
 
     /// Returns true if the trie is empty.
     pub fn is_empty(&self) -> bool {
         self.size() == 0
     }
+
+    /// Saves the trie to a file.
+    /// 
+    /// # Arguments
+    /// 
+    /// * `path` - The file path to save the trie to
+    /// 
+    /// # Errors
+    /// 
+    /// Returns an error if the trie cannot be saved to the file.
+    pub fn save<P: AsRef<Path>>(&self, path: P) -> Result<(), &'static str> {
+        let path_str = path.as_ref().to_string_lossy();
+        let c_path = CString::new(path_str.as_ref())
+            .map_err(|_| "Invalid path: contains null bytes")?;
+        
+        unsafe {
+            if marisa_trie_save(self.inner, c_path.as_ptr()) == 1 {
+                Ok(())
+            } else {
+                Err("Failed to save trie")
+            }
+        }
+    }
+
+    /// Loads a trie from a file.
+    /// 
+    /// # Arguments
+    /// 
+    /// * `path` - The file path to load the trie from
+    /// 
+    /// # Errors
+    /// 
+    /// Returns an error if the trie cannot be loaded from the file.
+    pub fn load<P: AsRef<Path>>(&mut self, path: P) -> Result<(), &'static str> {
+        let path_str = path.as_ref().to_string_lossy();
+        let c_path = CString::new(path_str.as_ref())
+            .map_err(|_| "Invalid path: contains null bytes")?;
+        
+        unsafe {
+            if marisa_trie_load(self.inner, c_path.as_ptr()) == 1 {
+                Ok(())
+            } else {
+                Err("Failed to load trie")
+            }
+        }
+    }
+
+    /// Memory-maps a trie file for read-only access.
+    /// 
+    /// This is more memory-efficient than loading the entire trie into memory.
+    /// 
+    /// # Arguments
+    /// 
+    /// * `path` - The file path to memory-map the trie from
+    /// 
+    /// # Errors
+    /// 
+    /// Returns an error if the trie cannot be memory-mapped from the file.
+    pub fn mmap<P: AsRef<Path>>(&mut self, path: P) -> Result<(), &'static str> {
+        let path_str = path.as_ref().to_string_lossy();
+        let c_path = CString::new(path_str.as_ref())
+            .map_err(|_| "Invalid path: contains null bytes")?;
+        
+        unsafe {
+            if marisa_trie_mmap(self.inner, c_path.as_ptr()) == 1 {
+                Ok(())
+            } else {
+                Err("Failed to memory-map trie")
+            }
+        }
+    }
+
+    /// Returns the size of the trie when serialized.
+    /// 
+    /// This can be useful for determining the storage requirements
+    /// before saving the trie to a file.
+    pub fn io_size(&self) -> usize {
+        unsafe {
+            let mut size: usize = 0;
+            if marisa_trie_io_size(self.inner, &mut size) == 1 {
+                size
+            } else {
+                0 // Return 0 if there's an error
+            }
+        }
+    }
+
+    /// Clears the trie, removing all keys.
+    /// 
+    /// After calling this method, the trie will be empty and
+    /// must be rebuilt from a keyset before it can be used again.
+    /// 
+    /// # Errors
+    /// 
+    /// Returns an error if the trie cannot be cleared.
+    pub fn clear(&mut self) -> Result<(), &'static str> {
+        unsafe {
+            if marisa_trie_clear(self.inner) == 1 {
+                Ok(())
+            } else {
+                Err("Failed to clear trie")
+            }
+        }
+    }
 }
 
 impl Drop for Trie {
@@ -330,4 +443,101 @@ mod tests {
         assert!(trie.is_empty());
         assert_eq!(trie.size(), 0);
     }
+
+    #[test]
+    fn test_save_and_load() {
+        use std::fs;
+        
+        let test_file = "test_trie.marisa";
+        
+        // Clean up from any previous test
+        let _ = fs::remove_file(test_file);
+        
+        // Build a trie
+        let mut keyset = Keyset::new();
+        keyset.push("apple");
+        keyset.push("application");
+        keyset.push("apply");
+        
+        let mut original_trie = Trie::new();
+        original_trie.build(&mut keyset).expect("Failed to build trie");
+        
+        // Test io_size
+        assert!(original_trie.io_size() > 0);
+        
+        // Save the trie
+        original_trie.save(test_file).expect("Failed to save trie");
+        
+        // Load the trie
+        let mut loaded_trie = Trie::new();
+        loaded_trie.load(test_file).expect("Failed to load trie");
+        
+        // Verify the loaded trie works the same
+        assert_eq!(loaded_trie.size(), original_trie.size());
+        assert!(loaded_trie.lookup("apple").is_some());
+        assert!(loaded_trie.lookup("application").is_some());
+        assert!(loaded_trie.lookup("apply").is_some());
+        assert!(loaded_trie.lookup("banana").is_none());
+        
+        // Test reverse lookup
+        if let Some(id) = loaded_trie.lookup("apple") {
+            assert_eq!(loaded_trie.reverse_lookup(id).unwrap(), "apple");
+        }
+        
+        // Clean up
+        let _ = fs::remove_file(test_file);
+    }
+
+    #[test]
+    fn test_mmap() {
+        use std::fs;
+        
+        let test_file = "test_mmap_trie.marisa";
+        
+        // Clean up from any previous test
+        let _ = fs::remove_file(test_file);
+        
+        // Build and save a trie
+        let mut keyset = Keyset::new();
+        keyset.push("memory");
+        keyset.push("mapped");
+        keyset.push("trie");
+        
+        let mut original_trie = Trie::new();
+        original_trie.build(&mut keyset).expect("Failed to build trie");
+        original_trie.save(test_file).expect("Failed to save trie");
+        
+        // Memory-map the trie
+        let mut mmapped_trie = Trie::new();
+        mmapped_trie.mmap(test_file).expect("Failed to mmap trie");
+        
+        // Verify the memory-mapped trie works
+        assert_eq!(mmapped_trie.size(), 3);
+        assert!(mmapped_trie.lookup("memory").is_some());
+        assert!(mmapped_trie.lookup("mapped").is_some());
+        assert!(mmapped_trie.lookup("trie").is_some());
+        assert!(mmapped_trie.lookup("nonexistent").is_none());
+        
+        // Clean up
+        let _ = fs::remove_file(test_file);
+    }
+
+    #[test]
+    fn test_clear() {
+        let mut keyset = Keyset::new();
+        keyset.push("test");
+        
+        let mut trie = Trie::new();
+        trie.build(&mut keyset).expect("Failed to build trie");
+        
+        assert_eq!(trie.size(), 1);
+        assert!(!trie.is_empty());
+        
+        // Clear the trie
+        trie.clear().expect("Failed to clear trie");
+        
+        assert_eq!(trie.size(), 0);
+        assert!(trie.is_empty());
+        assert!(trie.lookup("test").is_none());
+    }
 }
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 4bffc74..7da8725 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -47,4 +47,124 @@ fn main() {
     trie.predictive_search("app", |key, id| {
         println!("  Found: '{}' (ID: {})", key, id);
     });
+    
+    test_save_load_functionality(&trie);
+}
+
+fn test_save_load_functionality(original_trie: &Trie) {
+    println!("\n=== Save/Load Functionality Test ===");
+    
+    let test_file = "demo_trie.marisa";
+    
+    // Test io_size
+    let trie_size = original_trie.io_size();
+    println!("Original trie serialized size: {} bytes", trie_size);
+    
+    // Test save
+    println!("\nSaving trie to '{}'...", test_file);
+    match original_trie.save(test_file) {
+        Ok(()) => println!("✓ Trie saved successfully!"),
+        Err(e) => {
+            println!("✗ Failed to save trie: {}", e);
+            return;
+        }
+    }
+    
+    // Test load
+    println!("\nLoading trie from '{}'...", test_file);
+    let mut loaded_trie = Trie::new();
+    match loaded_trie.load(test_file) {
+        Ok(()) => println!("✓ Trie loaded successfully! Size: {}", loaded_trie.size()),
+        Err(e) => {
+            println!("✗ Failed to load trie: {}", e);
+            return;
+        }
+    }
+    
+    // Verify loaded trie functionality
+    println!("\n--- Verifying Loaded Trie ---");
+    let test_words = vec!["apple", "application", "banana"];
+    for word in &test_words {
+        let original_result = original_trie.lookup(word);
+        let loaded_result = loaded_trie.lookup(word);
+        match (original_result, loaded_result) {
+            (Some(orig_id), Some(load_id)) if orig_id == load_id => {
+                println!("✓ '{}' lookup matches (ID: {})", word, orig_id);
+            }
+            (None, None) => {
+                println!("✓ '{}' not found in both tries", word);
+            }
+            _ => {
+                println!("✗ '{}' lookup mismatch: orig={:?}, loaded={:?}", 
+                        word, original_result, loaded_result);
+            }
+        }
+    }
+    
+    // Test memory mapping
+    println!("\n--- Testing Memory Mapping ---");
+    let mut mmapped_trie = Trie::new();
+    match mmapped_trie.mmap(test_file) {
+        Ok(()) => {
+            println!("✓ Trie memory-mapped successfully! Size: {}", mmapped_trie.size());
+            
+            // Test a lookup on memory-mapped trie
+            if let Some(id) = mmapped_trie.lookup("apple") {
+                match mmapped_trie.reverse_lookup(id) {
+                    Ok(word) => println!("✓ Memory-mapped reverse lookup: ID {} -> '{}'", id, word),
+                    Err(e) => println!("✗ Memory-mapped reverse lookup failed: {}", e),
+                }
+            }
+        }
+        Err(e) => println!("✗ Failed to memory-map trie: {}", e),
+    }
+    
+    // Test clear functionality
+    println!("\n--- Testing Clear Functionality ---");
+    let mut test_trie = Trie::new();
+    let mut keyset = Keyset::new();
+    keyset.push("test");
+    keyset.push("clear");
+    
+    if test_trie.build(&mut keyset).is_ok() {
+        println!("Created test trie with {} keys", test_trie.size());
+        
+        // Test lookup before clear
+        let before_lookup = test_trie.lookup("test").is_some();
+        println!("Before clear - 'test' found: {}", before_lookup);
+        
+        // Clear the trie
+        match test_trie.clear() {
+            Ok(()) => println!("✓ Trie clear operation successful"),
+            Err(e) => {
+                println!("✗ Failed to clear trie: {}", e);
+                return;
+            }
+        }
+        
+        // Test after clear
+        println!("Testing trie state after clear...");
+        
+        let after_size = test_trie.size();
+        let is_empty = test_trie.is_empty();
+        let after_lookup = test_trie.lookup("test").is_some();
+        
+        println!("  Size after clear: {}", after_size);
+        println!("  Is empty after clear: {}", is_empty);
+        println!("  'test' found after clear: {}", after_lookup);
+        
+        if after_size == 0 && is_empty && !after_lookup {
+            println!("✓ Clear functionality works correctly!");
+        } else {
+            println!("⚠ Clear may not have worked as expected");
+        }
+    } else {
+        println!("✗ Failed to build test trie for clear functionality");
+    }
+    
+    // Clean up
+    match std::fs::remove_file(test_file) {
+        Ok(()) => println!("\n✓ Cleanup: Removed test file '{}'", test_file),
+        Err(e) => println!("\n⚠ Warning: Could not remove test file '{}': {}", test_file, e),
+    }
 }
diff --git a/wrapper.cpp b/wrapper.cpp
index 7fea9d2..8143b4a 100644
--- a/wrapper.cpp
+++ b/wrapper.cpp
@@ -82,9 +82,64 @@ int marisa_trie_predictive_search(const MarisaTrie* trie, MarisaAgent* agent) {
     }
 }
 
-size_t marisa_trie_size(const MarisaTrie* trie) {
-    const marisa::Trie* tr = reinterpret_cast<const marisa::Trie*>(trie);
-    return tr->size();
+int marisa_trie_size(const MarisaTrie* trie, size_t* size) {
+    try {
+        const marisa::Trie* tr = reinterpret_cast<const marisa::Trie*>(trie);
+        *size = tr->size();
+        return 1;
+    } catch (...) {
+        return 0;
+    }
+}
+
+int marisa_trie_save(const MarisaTrie* trie, const char* filename) {
+    try {
+        const marisa::Trie* tr = reinterpret_cast<const marisa::Trie*>(trie);
+        tr->save(filename);
+        return 1;
+    } catch (...) {
+        return 0;
+    }
+}
+
+int marisa_trie_load(MarisaTrie* trie, const char* filename) {
+    try {
+        marisa::Trie* tr = reinterpret_cast<marisa::Trie*>(trie);
+        tr->load(filename);
+        return 1;
+    } catch (...) {
+        return 0;
+    }
+}
+
+int marisa_trie_mmap(MarisaTrie* trie, const char* filename) {
+    try {
+        marisa::Trie* tr = reinterpret_cast<marisa::Trie*>(trie);
+        tr->mmap(filename);
+        return 1;
+    } catch (...) {
+        return 0;
+    }
+}
+
+int marisa_trie_io_size(const MarisaTrie* trie, size_t* size) {
+    try {
+        const marisa::Trie* tr = reinterpret_cast<const marisa::Trie*>(trie);
+        *size = tr->io_size();
+        return 1;
+    } catch (...) {
+        return 0;
+    }
+}
+
+int marisa_trie_clear(MarisaTrie* trie) {
+    try {
+        marisa::Trie* tr = reinterpret_cast<marisa::Trie*>(trie);
+        tr->clear();
+        return 1;
+    } catch (...) {
+        return 0;
+    }
 }
 
 MarisaAgent* marisa_agent_new() {
diff --git a/wrapper.h b/wrapper.h
index 9289af5..09e044a 100644
--- a/wrapper.h
+++ b/wrapper.h
@@ -25,7 +25,12 @@ int marisa_trie_lookup(const MarisaTrie* trie, MarisaAgent* agent);
 int marisa_trie_reverse_lookup(const MarisaTrie* trie, MarisaAgent* agent);
 int marisa_trie_common_prefix_search(const MarisaTrie* trie, MarisaAgent* agent);
 int marisa_trie_predictive_search(const MarisaTrie* trie, MarisaAgent* agent);
-size_t marisa_trie_size(const MarisaTrie* trie);
+int marisa_trie_size(const MarisaTrie* trie, size_t* size);
+int marisa_trie_save(const MarisaTrie* trie, const char* filename);
+int marisa_trie_load(MarisaTrie* trie, const char* filename);
+int marisa_trie_mmap(MarisaTrie* trie, const char* filename);
+int marisa_trie_io_size(const MarisaTrie* trie, size_t* size);
+int marisa_trie_clear(MarisaTrie* trie);
 
 // Agent functions
 MarisaAgent* marisa_agent_new();