To study the occurrence and radiograph features of the acetabular retroversion in hip dysplasia, and to evaluate the effects on the retroversion by the traditional maneuvers in the periacetabular osteotomy.Bernese periacetabular osteotomy was performed to 45 continuous dysplastic hips (43 patients) from December 2001 to November 2003. There were 37 female (39 hips) and 6 male (6 hips), average age was 28.9 (range, 15-45). The diagnosis of acetabular retroversion was based on the "cross-over" and "posterior wall" signs on the standard radiographs of the patients pre- or postoperatively.Among total 45 hips, the "cross-over" sign was positive in 8 hips, whereas including the "posterior wall" sign positive in 5 hips. The occurrence of retroversion was 17.8%. And the cross-over points were located within the superior 1/3 of the acetabulums in all cases. After the osteotomy, all the cross-over points moved to the inferior 1/3 of the acetabulums, and the "posterior wall" sign was seen in all 8 cases.Approximately one sixth of the patients with acetabular dysplasia have retroversion in which the superior 1/3 of the acetabulum faces posterolaterally. The retroversion can be identified with the standard AP pelvic radiographs. With the traditional maneuvers in periacetabular osteotomy, the retroversion will be aggravated in these patients.