diff --git a/problems/0235.二叉搜索树的最近公共祖先.md b/problems/0235.二叉搜索树的最近公共祖先.md
index b7e92e4e..b27a231e 100644
--- a/problems/0235.二叉搜索树的最近公共祖先.md
+++ b/problems/0235.二叉搜索树的最近公共祖先.md
@@ -513,6 +513,31 @@ impl Solution {
     }
 }
 ```
+### C#
+```C#
+// 递归
+public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q)
+{
+    if (root.val > p.val && root.val > q.val)
+        return LowestCommonAncestor(root.left, p, q);
+    if (root.val < p.val && root.val < q.val)
+        return LowestCommonAncestor(root.right, p, q);
+    return root;
+}
+// 迭代
+public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q)
+{
+    while (root != null)
+    {
+        if (root.val > p.val && root.val > q.val)
+            root = root.left;
+        else if (root.val < p.val && root.val < q.val)
+            root = root.right;
+        else return root;
+    }
+    return null;
+}
+```
 
 
 <p align="center">