The mallet finger has come to mean a particular deformity resulting from loss of extensor tendon continuity to the distal finger joint due to laceration, rupture and avulsion and is also observed commonly. There are conservative and operative treatment according to the conditions such as interval from injury to treatment and avulsion fracture. We used followed as interval from injury to treatment and avulsion fracture. We used followed treatment proctocols. In cases without fracture and within 4 weeks after injury, callus was excised and ruptured extensor tendon was repaired, In cases without fracture and with more than 4 weeks after injury, ruptured tendon was partially excised and ruptured extensor tendon was plicated. In case with fracture, avulsion fracture was reduced and fixed with K-wire, avoiding DIP joint injury. A clinical analysis was performed on the 29 cases with mallet fingers who had been treated at Soonchunhyang University Hospital from March 1986 to April 1990. The results obtained were as follows 1. Accrding to Hooper classification, type II was 19 cases (65.5%) and type III was 10 cases (34.5% ). 2. Interval from injury to treatment was average 2.3months and average follow up was 18 months. 3. According to Abouna criteria, 73% in type II and 30% in type III were satisfactory results (cured and improved). 4. Postoperative complications were superficial infection (2 cases) and pin tract infection(1 case).