diff --git a/HISTORY.md b/HISTORY.md
index cada00e60a..8e4083b28a 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -4,6 +4,7 @@
 
 - Fix: improve the type definitions of `ConstantNode` to support all data 
   types (#3257). Thanks @smith120bh.
+- Fix: #3259 function `symbolicEqual` missing in the TypeScript definitions.
 - Docs: fix broken links on the Configuration page. Thanks @vassudanagunta.
 
 # 2024-08-27, 13.1.1
diff --git a/test/typescript-tests/testTypes.ts b/test/typescript-tests/testTypes.ts
index 7538cad14c..c58e59ffb0 100644
--- a/test/typescript-tests/testTypes.ts
+++ b/test/typescript-tests/testTypes.ts
@@ -523,6 +523,22 @@ Chaining examples
     MathJsChain<MathNode>
   >()
 
+  // symbolicEqual
+  assert.strictEqual(
+    math.symbolicEqual(math.parse('x*y'), math.parse('y*x')),
+    true
+  )
+  assert.strictEqual(
+    math.symbolicEqual(math.parse('x*y'), math.parse('y*x'), {
+      exactFractions: true
+    }),
+    true
+  )
+  assert.strictEqual(
+    math.chain(math.parse('x*y')).symbolicEqual(math.parse('y*x')).done(),
+    true
+  )
+
   // slu
   expectTypeOf(
     math
diff --git a/types/index.d.ts b/types/index.d.ts
index 044611ec7d..fa7e4c9bad 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -1041,6 +1041,15 @@ export interface MathJsInstance extends MathJsFactory {
   simplifyConstant(expr: MathNode | string, options?: SimplifyOptions): MathNode
   simplifyCore(expr: MathNode | string, options?: SimplifyOptions): MathNode
 
+  /**
+   * Attempts to determine if two expressions are symbolically equal.
+   */
+  symbolicEqual(
+    expr1: MathNode,
+    expr2: MathNode,
+    options?: SimplifyOptions
+  ): boolean
+
   /**
    *  Replaces variable nodes with their scoped values
    * @param node Tree to replace variable nodes in
@@ -4888,6 +4897,15 @@ export interface MathJsChain<TValue> {
     options?: SimplifyOptions
   ): MathJsChain<MathNode>
 
+  /**
+   * Attempts to determine if two expressions are symbolically equal.
+   */
+  symbolicEqual(
+    this: MathJsChain<MathNode>,
+    expr2: MathNode,
+    options?: SimplifyOptions
+  ): MathJsChain<boolean>
+
   /**
    * Calculate the Sparse Matrix LU decomposition with full pivoting.
    * Sparse Matrix A is decomposed in two matrices (L, U) and two