A total of 6868 measurement on 414 hips of 207 normal child {95 (45.9%) boys and 112 (54.1%) girls] were evaluated in this study. AU length and its relation with epiphyses of femoral head was determined in order to achieve the diagnosis of developmental hip dysplasia in the roentgenogram where the epiphyses of the femoral head was not seen. According to our data, the average AU line length was 19.5.mm and standart deviation 1.86. it crossed through the center or 1-2 mm above the center of the epiphyses in 95.67% of the cases, and the epiphses center was in the middle of the line in 79.62%. In both hips of the girls acetabular index was 2°, shaft epiphyseal angle was 3.5°, and collo diaphyseal angle was 4° more than those of the boys whereas, center-edge angle was 4° higher in boys.