PURPOSE : The supracondylar fracture of the humerus is the most common elbow injury in children. They are commonly treated with closed reduction and percutaneous pin fixation. We measured the stability of supracondylar fractures, fixed with different configuration of pins, according to the each type of supracondylar fractures. MATERIAL AND METHOD : We reviewed 42 supracondylar fractures of the humerus in children that were treated with percutaneous pon fixtion from 1988 to 1997. The follow up period ranged from 1.5 to 41 months. The patient's average age was 9.2 years. The most common cause of injury was fall down injury in thirty three. The extension type is the most common, accounting for 95% of cases. We compared the initial post-op films with the follow up films which was checked at 2-3weeks later to establilish the stability by assessing the anterior beak prominence of the proximal fragment on lateral radiograph. RESULT : There were 8 cases of Type II-A (hyperextension post cortext intact AP, lateral appearance), 10 cases of Typer II-B (displaced/ angulated with osseous contact AP, lateral appearance) and 24cases of Type III(completely displaced AP, lateral appearance). The greatest stability was achieved with two crossed pons placed from the medial and lateral condyles. Final failure of the fixation occurred in two cases of the group II-B, fixed with only two lateral pins. CONCLUSION : The two crossed pins which were placed from the medial and lateral condyles provided the greatest stability of the fracture fragment. When we treat the type II-B pattern fracture (displaced/ angulated with osseous contact AP, lateral appearance), we must check the rotational stability after lateral pin fixation. If the fracture is unstable, we must fix the fracture with additional medial crossed pin fixation.