AIM:Technique for the fixation of two, three, and four part proximal humerus fractures has rapidly shifted towards the use of locking plates. The objective of this prospective study was to evaluate functional outcome and complications of proximal humeral fractures managed with proximal humerus internal locking system (PHILOS). METHODS: 16 men and 9 women aged 19 to 82 (mean, 49.24) with an acute proximal humerus fracture were treated with PHILOS plate by using deltopectoral approach. Outcome measurements included Constant score, complications, and radiographic assessment. RESULTS: 11 patients had 2-part fractures, 11 patients had 3-part fractures, and 3 patients had 4-part fractures. After 6 month follow up, a mean Constant score 57.4 was achieved. Outcomes were excellent in 16%, good in 44%, fair in 16% while poor in 24%. The Constant score was poorer for Neer type IV fractures as compared to other types. The most frequently occurring complications in our patients were malreduction 20%, screw perforation 16%, infection 12%, avascular necrosis 8%, frozen shoulder 8%, impingement 4% and plate pull out 4%. CONCLUSION: Fixation of proximal humerus fractures with proximal humerus locking plates is associated with satisfactory functional outcomes in 2-part and 3-part fracture. The incidence of complications and subsequent re-operation is relatively high. Advanced surgical skills and surgeon's experience are considered to be more critical for successful operative treatment.