Seventy-one consecutive patients were treated with a modified Steindler flexorplasty from 1970 to 1987. The mechanisms of injury and etiologies included 45 motor vehicle accidents, 13 birth injuries, and 13 cases of poliomyelitis. Additional operative procedures included shoulder fusion (45 patients), tendon transfer (20 patients), and wrist tenodesis (3). Follow-up averaged 8.2 years. The outcome was excellent in 32%, good in 47%, fair in 13%, and poor in 8%. Postoperatively, the mean arc of active elbow flexion was 114°; the average elbow extension loss, 28°; the mean active pronation, 74°; and supination, 30°. Wire breakage was found in two cases. Additional tendon transfer of flexor carpi ulnaris to extensor carpi radialis brevis improved the outcomes in the patients without active supination. The modified Steindler flexorplasty provided predictable functional improvement in carefully selected patients with paralyzed upper extremities.