The goals of treatment of the slipped capital femoral eiphysis(SCFE) are to stabilize the slipped epiphysis, prevent further slipping and induce early closure of the epiphyseal plate. Mutiple pinning was used for the treatment but in recent years, percutaneous in-situ fixation technique with 1 or 2 cannulated screws is preferred due to the advantages of low rate of complication such as pin penetration. We report the results of experimental study and the functional results after percutaneous pinning. The purpose of the experimental study was the investigation for changes of the screw length and the site of screw entry point according to the degree of slipping by bony model. The entry point of the screw was changed toward anterior and proximal portion of femoral neck and the length of inserting screw was changed to be shorter according to the degree of slip. We have treated 10 patients(13 hips) with slipped capital femoral epiphysis(SCFE) at our department since Jan. 1989. Among them, 6 patients(7 hips) could be followed for more than 2 years. There were 5 boys and 1 girl. One case was affected on the both hip. The average age at operation was 11.8 year old. All cases were obese. Degree of slipping was showed 6 cases in mild and 1 case in moderate. The slipping of acute onset was 3 cases, acute-on chronic 3 cases and chronic 1 case. In radiographic results, 6 cases were showing in Grade 0, 1 case was in Grade II. In functional results, 3 cases were excellent, 3 cases in good and 1 case in poor. One poor functional result was a case complicated by chondrolysis.