The objective of this work is to study the effect of Pemberton lateral acetabular osteotomy on acetabular development. The osteotomy was done for fifty- nine hips in 48 (11 bilateral and 37 unilateral) patients. The average age at the time of surgery was 1.9 years. The osteotomy was preceded by closed reduction in 18 hips, open reduction with varus derotation femoral osteotomy in 32 hips, and no treatment in 9 hips. The radiologic outcome according to the criteria of Severin was the corner stone in assessment of the results. At the final follow up period (average 4 years) for all the cases (59), there were: 46 hips with Severin class I (excellent), 10 hips with Severin class II (good), and 3 hips with Severin class III (fair). The final follow up values of acetabular index and centre edge angle were nearly the same for the normal and the operated abnormal hips in the unilateral cases. There was limited range of motion in one case but did not affect the daily activities. Our conclusion is that Pemberton acetabuloplsty can positively affect the growth and maturation of the acetabulum with residual developmental dysplasia.