INTRODUCTIONFractures of the proximal humerus are the most common fractures of this bone and constitute 5-6% of the total fracture incidence in adults; and this incidence increases with age.1 Complex fractures of the proximal humerus are often difficult to treat and result in considerable shoulder dysfunction unless adequately treated.2 According to the Neer's criteria for the proximal humerus fractures, fractures with fragments separated more than 1 cm or with more than 45 degree angulation are considered as displaced fractures; 3,4 and hence need open reduction and internal fixation. Most of the surgeons are familiar with the traditional deltopectoral approach, which utilizes the internervous plane between the pectoralis major and the deltoid; and hence this is the most commonly used approach for proximal humerus fracture fixation. 2 But in certain fractures in which the fragments especially the greater tuberosity fragment is displaced, usually posterolaterally, reduction through this approach is difficult. In addition, the application of plates on the lateral surface of proximal humerus requires a lot of soft tissue dissection and retraction. Hence an access from the lateral aspect would be far more convenient in certain circumstances. The transdeltoid or the deltoid splitting ABSTRACT Background: The deltopectoral approach is the most commonly used approach for the reduction and fixation of proximal humerus fractures. But it provides inadequate access to the posteriorly displaced fragments in comminuted fractures and to the lateral surface where the plate is to be applied. These disadvantages can be obviated by a direct lateral transdeltoid approach. There have been concerns regarding postoperative axillary nerve palsy and deltoid dysfunction with this approach. This study had been conceptualized to assess the outcome of fixation of proximal humerus fractures with deltoid splitting lateral approach. Methods: A total of 20 patients with Neer's type 2 and 3 fractures of proximal humerus were included in this study. Lateral transdeltoid approach was used for exposure, with either an extended incision or a "two window" less invasive incision, depending upon the fracture anatomy. Functional outcome was assessed using the Constant Murley shoulder score. Results: The fracture was classified as Neer's type 2 in 30% and type 3 in 70% of the cases. The mean Constant Murley score at final follow up was 78 (range 64-84). Graded according to the Constant shoulder score grading criteria, the results were excellent in 60%, good in 35% and fair in 5% of the cases. No case of postoperative axillary nerve palsy was encountered. Conclusions: The functional outcome was either excellent or good in 95% of the cases and no case of axillary nerve palsy was seen. Hence, Lateral transdeltoid approach is a convenient and useful approach to proximal humerus fractures.