Six cases of isolated avulsions of the lesser tuberosity of the humerus were encountered within a short period of time. Although it seldom has been described in the literature, it might be a more common fracture than suspected. Physical examination revealed a painful shoulder with limited function in all six patients. In retrospect, all diagnoses could have been made on the primary plain roentgenograms. However, the fragment of the lesser tuberosity was easily misdiagnosed. An axillary view showed the fragment clearly in all cases. Computed tomography is useful for making an accurate diagnosis because it establishes the size and displacement of the fragment and determines additional injuries, such as a ruptured biceps tendon. Five patients with displacement of the lesser tuberosity were operated on after several weeks or months. The lesser tuberosity was reattached in all cases. After 6 months three patients had slight impairment of elevation and external rotation, and one of them suffered from pain during movements of the arm. The patient with no fracture displacement was treated conservatively with a good result. In conclusion, we recommended an axillary roentgenogram as part of the posttrauma radiologic series of the shoulder. A nondisplaced avulsion fracture of the lesser tuberosity of the humerus can be treated conservatively. We recommend reattachment of displaced fractures.