We have reviewed thirteen cases of fracture-separation of the distalk humeral epiphysis, one of which was initially misdiagnosed as a fracture of the lateral condyle. There were some difficulties in making the correct diagnosis. The injury must be distinguished from anelbow dislocation and a fracture of the lateral humeral condyle. All thirteen patients revealed posteromedial displacement of the distal humeral epiphysis on initial x-rays nine patients were treated by colosed reduction and cast Immobilizatlon, and four patients by open reduction and internal fixation All nine patients with conservative treatment had slight cubitus varus under 5 degrees. Two patients with operative treatment had significant deformities of the elbow, one 25 degrees of valgus and one 20 degrees of varus. In treatment of these injuries, accurate evaluation of the state of reduction is important but difficult to obtain. We got acceptable results with conservative treatment.