The incidence of olecranon fractures in adults and the long-term outcome of closed olecranon fractures in 45 women and 28 men (mean age, 54 and 36 years at the time of fracture, respectively), were examined at a mean of 19 years after the fracture. The uninjured elbows served as controls. Thirteen percent of the original fractures were displaced less than 2 mm, 65% more than 2 mm, and 22% were multifragmental. Primary treatment consisted of mobilization in 4%, application of a plaster cast in 12%, and open reduction and internal fixation in 84% of the elbows. The incidence of an isolated fracture of the olecranon in individuals older than 16 years was 1.15 per 10,000 person-years. Eighty-four percent of the 73 patients had no complaints at followup, 12% had occasional pain, and 4% had daily pain. Ninety-six percent had an excellent or good outcome. Elbow flexion and extension were reduced but most patients had no or only occasional subjective complaints. Radiographic signs of degenerative changes were found in more than 50% of the formerly fractured elbows, which was more than in the uninjured (11%). Radiographic signs of osteoarthritis were found in 6% of the formerly fractured elbows versus zero percent in the uninjured, of which only two patients had a poor outcome. Isolated, closed fractures of the olecranon in adults have a favorable, long-term outcome.