In patients who have a malunion of the distal part of the radius with a shortened radius, the ulna is too long. A discrepancy between the ulna and the lower radius, and between the ulna and the carpal bones occurs, compromising the mobility and appearance of the wrist. We reviewed ten such patients in whom the ulna was shortened by performing a resection of a diaphysar cylinder followed by a plate osteosynthesis. This method restored the normal anatomy of the distal radio-ulnar joint, markedly reduced the patient's pain and improved pronation and supination. When performed in young patients, when the radial deformity is not very important, this procedure has most satisfying functional results.