At operation for the correction of cubitus varus by removal of a wedge based laterally, the radial nerve fortunately was first explored and found to run through a transverse bony tunnel at the posterior level of a supracondylar fracture sustained eight years previously. After elevation of the bony tunnel and nerve en bloc the osteotomy was completed; neurapraxia of the radial nerve soon recovered. With hindsight, the entrance and exit foramina of the tunnel could be clearly seen in the antero-posterior radiograph taken before the operation.