The risk of avascular necrosis, nonunion, or malunion is high in osteoporosis-related 4-part fractures. We tried to evaluate the results of patients who underwent plate osteosynthesis with vascularized pectoralis major graft comparing with tricortical iliac grafting to treat 4-part proximal humerus fractures. Thirty-four patients aged 50-75 with Neer 4-part proximal humerus fractures were studied. Group A (n=17) underwent osteotomy of a 2.5cm±1cm pectoralis major pedicle bone graft and plate application, while Group B (n=17) underwent plate osteosynthesis using iliac autogenous grafts. Final follow-up assessments included evaluation using Constant and American Shoulder and Elbow Surgeons scoring systems, Humeral Neck-Shaft Angle (HNSA), humeral head height (Humeral Head Height) and humeral head avascular necrosis. Although reduction loss was observed in 3 patients (17.6%) in Group A patients, reduction loss was observed in 10 patients (58.8%) in Group B., p= 0.013. Humeral head avascular necrosis was 1 (5.8%) in Group A, while it was 5 (29.4%) in the other group (p= 0.071). The HNSA was normal in 12 (70.5%) of Group A patients, while it was normal in 6 (35.2%) of Group B patients. The HNSA was weak or bad (<1200) in 29.4% of Group A patients, while this rate was 64.7% in Group B patients. HHH was 2.64±1.45 mm in Group A and 3.66±1.65 mm in Group B. There were no statistically significant differences between the two groups in terms of Constant and American Shoulder and Elbow Surgeons scoring systems. Pectoralis major bone pedicle graft in Neer 4-part proximal humerus fractures reduces the risk of avascular necrosis and nonunion rates. Our technique yielded excellent clinical and radiological results. We achieved recovery without creating additional donor site morbidity.