diff --git a/7-reverse-integer/7-reverse-integer.cs b/7-reverse-integer/7-reverse-integer.cs
new file mode 100644
index 0000000..86181be
--- /dev/null
+++ b/7-reverse-integer/7-reverse-integer.cs
@@ -0,0 +1,24 @@
+public class Solution {
+    const int INT_MAX = 2147483647;
+    public int ReverseHelper(int x, int reversed) {
+        if (reversed > (int) (INT_MAX / 10)) {
+            return 0;
+        }
+        
+        if (x < 10) {
+            return reversed * 10 + x;
+        }
+        
+        return ReverseHelper(x / 10, reversed * 10 + x % 10);
+    }
+    
+    public int Reverse(int x) {
+        if (x == - INT_MAX - 1) {
+            return 0;
+        }
+        else if (x < 0) {
+            return -1 * ReverseHelper(Math.Abs(x), 0);
+        }
+        return ReverseHelper(Math.Abs(x), 0);
+    }
+}
\ No newline at end of file