The authors have experienced forty-two patients of congenital dislocation of the hip from the Department of Orthopaedic Surgery, Guro Hospital, the Korea University College of Medicine since September, 1983, four of which were bilaterally involved. An analytical study was made with these bilateral cases, and the following observations were obtainable. 1. The incidence of bilateral involvements in reference to total number of cases was 9.8%(4/42) which is remarkably lower than those of western reports. 2. Diagnosis was generally delayed for bilateral involvements until 2.5 years of age in average which is 1 year later than for the unilaterals. 3. Presenting signs were mostly waddling gait and abnormal posture other than asymmetric abduction and limping gait which were those of unilaterals. 4. The incidence of other congenital abnormalities in association was observed to be much higher than that of unilaterals. 5. According to Gibson & Benson's modification of Severin’s classification the postoperative results at 23 months follow-up in average were assessed less satisfactory than those of unilaterals having 2 cases in clinical group 2-X-ray grade II, 1 cases in clinical group 3-X-ray grade II, and 1 case in clinical group 3-X-ray grade III.