The author have analyzed clinical and radiological materials of foully-five patients of lateral condylar fracture of the humerus who have been treated with close reduction and percutaneous pinning after arthrogram, open reduction and internal fixation and followed up for more than 6 month since September, 1993. If the fracture is incomplete will not be displaced after varus and valgus stress. Also We have checking arthrogram of reduction state. we have treated with close reduction and percutaneous pinning. If the fracture is complete the fragment may be displaced and open reduction with internal fixation is mandatory, the following results were obtained: 1. Age at diagnosis was 5.7 years in average ranging from two years to twelves years. thirty-three out of fourty-five children(73.3%) were male to reveal definite male prepoderance. 2. As for Milch type classification, three cases(5%) were of type I and foully two cases(95%) were of type II. According to Jakobs staging of displacement, 7 cases were of stage I, 25 cases were of stage II , and 13 cases were of stage III. 3. The open reduction were indicated as follows: Jak obs stage II unreduced, postinjury 48 hours relapsed, Jakob stage III. The closed reduction were indicated as follows: Jakobs stage I, II Badelon type I, II and undisplaced and reduceable with supination-valgus stress view, arthrogram. 4. The average period of postoperative cast immobilization was 4 weeks, active and gentle passive motion exercises were instituted thereafter. 5. The range of change in carrying angle was not influenced by degree of fragment displacement and method of treatment. 6. The complications were lateral condylar overgrowth(6 cases) and avascular necrosis(1 case). 7. The result of the treatment classified according to Hardacre assessement, were excellent in thirty one cases(69%), good in thirteen cases(29%), poor in one case(2%). In conclusion, the closed reduction and internal fixation with arthrogram, is considered as the treatment of choice for the minimally displaced lateral condylar fractures of the humerus in children.