A brief anatomical review of the ulnar nerve and areas of ulnar nerve entrapment is discussed. The importance of the dorsal cutaneous nerve is presented with regard to localizing a lesion to the ulnar nerve in the forearm. A classification system is described for ulnar entrapment that occurs distal to the wrist. The case of a nine-yearold girl with a fibrous entrapment of the ulnar nerve in the distal ulnar tunnel is presented. The clinical and diagnostic procedures required for localizing the level of the ulnar nerve entrapment are described, along with the operative findings of this case report.