In a prospective population-based study of all shoulder injuries seen at Malmö General Hospital during 1987, the incidence and causes of major injuries involving fractures of the clavicle, scapula, or proximal humerus and glenohumeral or acromioclavicular dislocations were investigated in children, adults, and the elderly. Seventy-five shoulder injuries occurred in children. Sixty-five of them were fractures of the clavicle. In this age group no sex-related differences were seen in incidence, and 37 of 73 injuries were related to sports or playing. One hundred eighty-one injuries occurred in adults. Sixty fractures of the proximal humerus, 67 fractures of the clavicle, and 31 primary glenohumeral dislocations were seen. The injuries in this group were significantly more frequent in men, with most of them caused by traffic and sport injuries. Two hundred forty-eight injuries occurred in elderly people. Two hundred one were fractures of the proximal humerus. The incidence was significantly higher in women; 147 of 247 injuries were caused by an indoor fall. The variations among age groups are probably attributable to age-related differences in activity, mobility, and fragility.