Background: The purpose of this prospective study was to assess the short- and long-term outcome of proximal humerus fractures treated according to a standardized regime. Patients and Methods: 99 patients with fractures of the proximal humerus were included. Scapular anteroposterior and lateral radiographs were used to classify the fracture type with the Neer classification system. Treatment was nonoperative and included a sling for 4-6 weeks followed by 6 weeks of physical therapy. Functional ability and patients' satisfaction, the main parameters to check whether our regime was acceptable, were tested at 6 weeks, 3, 6 and 12 months, and 5 years after the initial injury. Results: 3 months after the initial injury, patients had reached a mean flexion and abduction of 107° and 96°, respectively. Progression in functionality was mostly gained in the period of admittance to physical therapy. Thereafter, functional ability remained rather constant. Complications, including dystrophy, necrosis of the humeral head and malunion of the fracture, occurred in 4% of all patients. 87% of the surviving patients were still satisfied with the clinical outcome of the treatment at 5 years from the injury. Mortality after approximately 5 years of follow-up was 35% which proved significantly higher than the mortality in an age-adjusted healthy population. Conclusions: From the results of this study we conclude that, in general, fractures of the proximal humerus can be successfully treated nonoperatively by following a standardized regime including 6 weeks of physical therapy.