This report presents a case of direct injury to the dorsal sensory branch of the ulnar nerve caused by arthroscopic repair of the triangular fibrocartilage complex. The dorsal sensory branch of the ulnar nerve was strangulated by one of the three pull-out sutures of the joint capsule, just ulnar to the extensor carpi ulnaris tendon. Pain and dysaesthesia of the ulnar side of the wrist was completely relieved after excision of the injured nerve segment. This complication can be avoided by careful exploration of the dorsal sensory branch of the ulnar nerve prior to suturing or passage of instruments during arthroscopy.