A 19-year-old female collegiate swimmer presented to our sports medicine clinic with a history and physical examination consistent with right ulnar neuropathy at the cubital tunnel. Diagnostic ultrasound (US) revealed compression of the ulnar nerve under the cubital tunnel retinaculum (CTR) with nerve swelling proximal to the site of compression. Electrodiagnostic studies confirmed the diagnosis of a moderate to severe ulnar neuropathy at the elbow. Treatment consisted of an US-guided decompression of the ulnar nerve in the cubital tunnel by cutting the CTR using a rotated stylet "v" cutting technique. The patient's symptoms resolved, and she was able to begin a swimming progression 2 weeks after the procedure. After completion of this progression, she was able to successfully resume full, unrestricted competitive collegiate swimming without return of her symptoms. To the best of our knowledge, this is the first description of an US-guided cubital tunnel decompression surgery.