Mallet finger is a common deformity caused by discontinuity of the extensor mechanism at the distal interphalangeal joint. The loss of 1mm of excursion of extensor tendon at the distal phalanx may result in 20–30 percentage loss of motion. Surgical repair are made defficult by slimness and thin of the extensor tendon, Anatomical reduction of tendon length or bony fragment was important factor for successful results. From Jan, 1984 to Jul. 1991, we experienced 33 operations for mallet fingers. The results were summarized as follows: 1. The 3rd finger was the most commonly involved (33.3%), followed by the 4th finger and the most common cause was direct blow (57.6%). 2. According to the Doyle's classification, the most common type was type I (33.3%), followd by the type IVB(30.3%), and 25 (75.8%) of 33 cases were showed to be satisfactory results, but there were no satisfactory results in tyep III. 3. The mode of injury, amount of damage, anatomical reduction of the tendon length or bony fragment and cooperation of the patient are thought to be related to the results.