The first metacarpal base fracture is classified as extra-articular fracture, intra-articular fracture and epiphyseal injury. Intra-articular fracture was firstly described in 1882 by Bennett and Rolando described about Y shape comminuted fracture in the first metacarpal base in 1910. In 1938, Robert wrote about oblique fracture injured by first metacarpal base fracture. First metacarpal base fracture can be adjusted easily by C/R, but it is difficult to maintain the good axis. In case of fail of reduction, malunion, joint stiffness and traumatic arthritis can be shown as complications and finally some problems in grasping and pinching are resulted. Therefore, firstly the most accurate reduction, secondarily effective method to maintain the condition and thirdly the protection of limitation of motion are goal of treatment. Authors reviewed 17 cases treated by 0/R & C/R for the past 5 years from 1975 to 1980 at National Medical Center, especially reviewed the cases of which observation more than 1 year was possible. The results were as followings: 1. The incidence of first metacarpal base fracture was 1.0% of all fractures & dislocations. 2. Out of 17 cases, there were 14 male and right side 9 cases and left side was 8 cases. 3. The most common case of fracture was injury at work and traffic accident, sports injury, slipping down and falling down. 4. The method of treatment were C/R & percutaneous pinning in 10 cases and 0/R & K-wire fixation were 7 cases. 5. The result of treatment showed 8 excellent, 1 good, 1 fair, out of 10 cases of C/R and percutaneous pinning. In 0/R and K-wire fixation, 4 excellent, 2 good, and 1 fair showed out of 7 cases. 6. Soft tissue infection was appeared from 1 case of open fracture which accompanied second metacarpal fracture as complication and it caused adduction contracture in first web space.