Object The aim of this retrospective study was to evaluate the restoration of shoulder function by means of supra-scapular nerve neurotization in adult patients with proximal C-5 and C-6 lesions due to a severe brachial plexus traction injury (BPTI). The primary goal of brachial plexus reconstructive surgery was to restore the biceps muscle function and, secondarily, to reanimate shoulder function. Methods Suprascapular nerve neurotization was performed by grafting the C-5 nerve in 24 patients and by accessory or hypoglossal nerve transfer in 29 patients. Additional neurotization involving the axillary nerve could be performed in 18 patients. Postoperative needle electromyography studies of the supraspinatus, infraspinatus, and deltoid muscles showed signs of reinnervation in most patients; however, active glenohumeral shoulder function recovery was poor. In nine (17%) of 53 patients supraspinatus muscle strength was Medical Research Council (MRC) Grade 3 or 4 and in four (8%) infraspinatus muscle power was Grade 3 or 4. In 18 patients in whom deltoid muscle reinnervation was attempted, MRC Grade 3 or 4 function was demonstrated in two (11%). In the overall group, eight patients (15%) exhibited glenohumeral abduction with a mean of 44 ± 17° (standard deviation SD) (median 45°) and four patients (8%) exhibited glenohumeral exorotation with a mean of 48 ± 24° (SD) (median 53°). In only three patients (6%) were both functions regained. Conclusions The reanimation of shoulder function in patients with proximal C-5 and C-6 BPTIs following supra-scapular nerve neurotization is disappointingly low.