We studied 28 displaced (Jacob types II and III) fractures of the lateral humeral condyle in 28 children. There were only two Milch type I fractures. Twenty-one fractures were treated by open reduction and internal fixation with K-wires, Palmer nails, or sutures. Seven patients were treated with a plaster cast, five following closed reduction, and the primary displaced position being accepted in two. Anatomic reduction was obtained in 18 patients. All but one fracture were united at review 2 years to 16 years later. The distal humerus was wider on the injured side in all patients. Six patients had a visible varus deformity, and three patients had a visible valgus deformity. The radiologic tilt of the joint surface and the depth of the trochlear groove were measured in patients more than 10 years old at review. All patients with a final varus tilt of the joint surface on the injured side were less than 9 years of age at injury, and all but one of the patients with Milch type II fractures had a deepening of the trochlear groove. Two patients developed avascular necrosis of the trochlea. One of these had a concomitant fracture of the medial humeral epicondyle, and the other suffered a lateral condylar fracture preceded by a supracondylar fracture. We conclude that a reduced growth potential at the trochlear groove is a regular complication of the Milch type II fracture, and that the Jacobs classification is the most useful in the assessment of the method of treatment.