A case of acute compression neuropathy of the median nerve associated with haemorrhage into the carpal tunnel is presented. The condition occurred spontaneously in a patient on Warfarin for previous deep venous thrombosis. The signs and symptoms were those of acute tenosynovitis originating in the common flexor synovial sheath at the wrist with associated paraesthesia in the distribution area of the median nerve in the hand. The patient was afebrile and blood tests were normal.