diff --git a/csharp/226-Invert-Binary-Tree.cs b/csharp/226-Invert-Binary-Tree.cs
new file mode 100644
index 000000000..ec517ad24
--- /dev/null
+++ b/csharp/226-Invert-Binary-Tree.cs
@@ -0,0 +1,29 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public int val;
+ *     public TreeNode left;
+ *     public TreeNode right;
+ *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+public class Solution
+{
+    public TreeNode InvertTree(TreeNode root)
+    {
+        if (root == null) return null;
+
+        var tmp = root.left;
+        root.left = root.right;
+        root.right = tmp;
+
+        InvertTree(root.left);
+        InvertTree(root.right);
+
+        return root;
+    }
+}
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