Four patients with long-standing Kienböck's disease were treated by excision of the lunate and with dorsal flap arthroplasty. All patients had had unsuccessful attempts at conservative therapy. On follow-up, averaging twenty-eight months, all were symptom free and had returned to hobbies and athletic activities. The dorsal flap operation prevented the carpal migration which occurs with mere extirpation of the lunate and is preferable to inserting a prothesis or interposing other tissue. The morbidity and complications were less than are encountered either in intercarpal fusion or in the ulnar lengthening operation or in wrist arthrodesis.