Three-dimensional assessment of acetabular coverage of the femoral head was made for 30 patients with unilateral congenital dislocation of the hip undergoing Salter's innominate osteotomy for residual subluxation. Radiologic examinations were serially performed until bone maturity, and the final acetabular coverage was evaluated by a quantitative method with a computer program developed by Konishi and Mieno. At the final examination, no significant differences between the involved and unaffected sides were found in terms of the total coverage or posterior-half coverage. The anterior-half coverage and the anterior-to-posterior ratio of the involved side were significantly greater (73.7 and 97.8%, respectively) than the values for the unaffected side (68.8 and 90.8%). In conclusion, the anterior inclination of distal fragment that is obtained by Salter's innominate osteotomy continues until bone maturation. However, remodeling of the posterior part of the acetabulum occurs by growth after the operation.