UNLABELLED The purpose of this study was to define the acetabular changes associated with coxa vara and determine how these acetabuli differ from those of a normal hip. Charts and radiographs of 33 patients with coxa vara with a mean age of 6 years (range, 2-15 years) were retrospectively reviewed. The diagnosis was developmental coxa vara in 21 patients and congenital femoral deficiency in 12. Radiographic measurements, including acetabular index, sourcil slope, center edge angle, migration index, and medial joint space, were compared with those of 29 hips in the control group. The inclination of the acetabulum or acetabular slope (as measured by the acetabular index and sourcil slope) was significantly increased in the hips with coxa vara as compared with those in the control group. Both parameters have a statistically significant inverse correlation with the degree of varus, ie, the greater the varus of the proximal femur, the greater the upsloping of the acetabulum. Joint subluxation, as measured by the center edge angle, migration index, and medial joint space, showed little difference from that of control subjects. LEVEL OF EVIDENCE Level III, diagnostic study.