Eight patients with flexor paralysis of the elbow due to a lesion of the brachial plexus (two cases) and to poliomyelitis (six cases) were treated by transplantation of the latissimus dorsi muscle which was detached at both ends and transferred to replace the biceps, preserving its long and lax neurovascular pedicle. Thirteen months to six years after operation, the strength and flexion of the elbow were very satisfactory. This flexorplasty, one of the best available, should be performed only after a complete study of the patient's general functional needs and the condition of the affected arm.