Introduction: There is no consensus on the treatment of proximal humeral fractures. The goal of the present retrospective observational study was to compare functional and radiological results and complications of internal fixation using locking plates versus antegrade nailing in the treatment of non-osteoporotic Neer classification 3- and 4-part fractures after a least 1 year of follow-up. Material and methods: Internal fixation was performed in 67 fractures (1 bilateral): 35 by locking plate (1 lost to follow-up, 1 deceased) and 32 by intramedullary nailing (2 lost to follow-up) between January 1st, 2004 and December 31st, 2010. Thus, the study included 33 plates (21 3-part and 12 4-part fractures) and 30 nails (21 3-part and nine 4-part fractures). Final functional assessment was based on the Oxford, Constant, Relative Constant and QuickDASH scores and percentage of handicap. Radiological follow-up included immediate postoperative, 6 weeks, 3 months and 1 year AP and Lamy lateral views. All complications were recorded prospectively. Results: Mean Oxford, Constant, Relative Constant and QuickDASH scores and percentage of disability for the plate and nail groups respectively were: 23.8 vs. 23.3, 59.7 vs. 60 6, 73.5 vs 79.3, 20.9 vs 21.0, 22.6 vs 22.6. Multivariate analysis did not show any significant difference in functional scores or quality of reduction: final unsatisfactory reduction on AP view, 30.3 vs. 36.7%; lateral view, 3.2 vs. 10.0%; greater tuberosity, 9.1 vs. 16.7%. Four-part fracture (13< 0.05), frontal reduction defect at follow-up (13< 0.05) or greater tuberosity defect (A > 0.05) had negative impacts on functional scores. The complication rates corresponded to those in the literature and did not differ between the techniques (P=0.1901) except for three infections in the plate group. Discussion- Conclusion: Internal fixation is the treatment of choice for 3- and 4-part fractures in nonosteoporotic patients. Although no difference was found in the present study between locking plate and intramedullary nailing, the former seems to be less well adapted and more aggressive. Type of study: Retrospective observational study. Level of evidence: Level 4. (C) 2014 Elsevier Masson SAS. All rights reserved.