Mallet finger is a commom deformity caused by disruption of the extensor mechnism at the dorsal base of the distal phalanx. Patients can by managed by either conservative or operative treatment depending on some factors, such as the fracture type and interval from injury to medical treatment. However, whether to perform conservative or operative treatment is in debate. We conducted this study to compare the results of conservative and operative treatment of mallet finger caused by intra-articular fracture of the distal phalanx, with not mere than one third of the articular surface of the distal phalanx involved. From March 1994 to April 1999, we experienced 26 cases of bony mallet fingers. Following are the results. 1. The result by Kanies scale was satisfactory in 9 cases of 12 in conservative treatment(75%), and 10 cases of 14 in operative treatment(71%)(P>0.05). 2. The result was satisfactory in 8 cases of 10 in patients who were treated within 2 weeks(80%), and 4 cases of 7 in those treated after 4 weeks(57%)(P<0.05). 3. Conservative treatment was more cost effective, easier to perform compared to operative treatment. Thus, we suggest conservative treatment as the better treatment method for bony mallet finger with ont more than one third of the articular surface of the distal phalanx involved.