diff --git a/cs/maximum-nesting-depth-of-the-parentheses.cs b/cs/maximum-nesting-depth-of-the-parentheses.cs
new file mode 100644
index 0000000..656cd82
--- /dev/null
+++ b/cs/maximum-nesting-depth-of-the-parentheses.cs
@@ -0,0 +1,21 @@
+public class Solution {
+    public int MaxDepth(string s) {
+        int maxDepth = 0;
+
+        int open = 0;
+        foreach (var c in s) {
+            switch (c) {
+                case '(':
+                    ++open;
+                    break;
+                case ')':
+                    --open;
+                    break;
+            }
+
+            maxDepth = Math.Max(maxDepth, open);
+        }
+
+        return maxDepth;
+    }
+}