A study was undertaken to assess functional outcome in 11 patients undergoing latissimus dorsi and teres major transfer (L'Episcopo procedure) for external rotation deficient shoulders. The mean age was 37 years (range 18 to 48 years). All of the patients had adult-onset brachial plexus injuries. The mean time for injury to operation was 32 months. Patients were evaluated by questionnaire, measurement of the range of motion, strength testing, and an overhead work simulation. Of the patients studied, 10 of the 11 patients were working (8 returned to their preinjury employment). The cumulative postoperative mean activities of daily living score was 20 (maximum possible 33) compared with 14 before surgery. No complications occurred. Ten patients reported confidence in the limb and believed the procedure was worthwhile. Mean active external rotation of the shoulder at 0 degrees and 90 degrees elevation was 28 degrees (range 15 degrees to 55 degrees and 36 degrees (range 0 degrees to 90 degrees), respectively. Postoperative external rotation strength was 0.32 that of the control side with the arm at the side. Seven of the nine patients tested were able to complete the Valpor overhead work simulation. The L'Episcopo muscle-tendon transfer reliably improves functional outcome in the late functional reconstruction of adult-onset brachial plexus lesions.