The importance of external rotation of the shoulder is well accepted. Patients with inadequate recovery of shoulder function after nerve transfers for a brachial plexus injury have difficulty in using their reconstructed limb. The options for secondary procedures to improve shoulder function are often limited, especially if the spinal accessory nerve has been used earlier for nerve transfer or as a donor nerve for a free functioning muscle transfer. We have used the contralateral lower trapezius transfer to the infraspinatus in three cases, to restore shoulder external rotation. All patients had significant improvement in shoulder external rotation (mean 97°; range 80°–110°) and improved disability of the arm, shoulder and hand scores. The rotation occurred mainly at the glenohumeral joint, and was independent of the donor side. All patients were greatly satisfied with the outcome. Contralateral lower trapezius transfer appears to help in overall improvement of shoulder function by stabilizing the scapula. The results have remained stable after mean follow-up of 58 months (range 12–86). No donor site deficit was seen in any patient.