This study evaluated the change of carrying angle and the causes of cubitus varus after the fracture separation of the distal humeral epiphysis in young children. Twelve cases of fracture separation of distal humeral epiphysis were treated from January 1995 to July 1997. The age of all patients was younger than 3 years old. A metaphyseal fragment was seen in all cases (Salter-Harris type II), but the size of the metaphyseal fragment was either a very small flake or a large Thurston-Holland fragment. Posteromedial displacement was seen in all cases. There were three treatment groups: closed reduction with percutaneous pinning, closed reduction with cast, and cast without reduction. Follow-up period averaged 23.5 months (range, 12-40). Cubitus varus deformity was seen in seven cases, and six of them had a partial defect of the medial condyle that was avascular necrosis. The methods of treatment, age of injury, and the type of epiphyseal injury had no influence on the development of cubitus varus, but avascular necrosis of the medial condyle was related to the cubitus varus deformity (p<0.05). The results of this study suggest that fracture separation of distal humeral epiphysis in young children is likely to produce cubitus varus deformity with the development of avascular necrosis of the medial humeral condyle.