PURPOSE: This retrospective study was performed to know the clinical results after closed reduction and open reduction for completely displaced supracondylar fractures of distal humerus in children. MATERIALS AND METHODS: Twenty-eight cases of this injury at the mean age of 6.4 (range 21- 138 months), have been followed up over the minimum of one year. The types according to the position of displacement were 15 in posteromedial, and 13 in posterolateral displacement. There were 4 cases of associated nerve palsies (3;median, 1; radial). We tried the closed reduction (17 cases), but open reduction (11 cases) was indicated in irreducible cases with or without severe swelling. Then, the fractures were stabilized by percutaneous K-wires with lateral (23 cases) or cross pinning (5 cases). The differences of Baumann's angle, humero-ulnar angle, and elbow motion to uninjured side were calculated, and Flynn's criteria was used for evaluation. RESULTS: All fractures were united without any infection or soft tissue compromise. The symptoms of injured nerve recovered within 8 weeks. According to Flynn's cirteria, results were excellent in eleven, good in 12, fair in 2, and poor in 3. The rates of satisfactory results over good were similiar between closed and open reduction, and the other factors including age and type of displacement were not meaningful. The mean Baumann's angle was 8.7 in closed and 6.6 in open reduction group. None of the patients showed restricted elbow motion above 10 degrees, even in 3 cases of hypertrophic scars in the group of open reduction. CONCLUSION: The selective use of open reduction in completely displced supracondylar fractures of distal humerus in children, would show results as good as closed reduction.