The authors have experienced twelve infants who were referred with impression of congenital dislocation of the hip initially, but found to have pelvic obliquity later at Department of Orthopaedic Surgery, the Korea University Guro Hospitsl. An analytic study with these csses is made and to be reported with review of references as follows. 1. Among 12 cases, 4 cases were male snd 8 cases were female. The sverage age was 3.3 months ranging from 10 days to 5 months. 2. Moulded baby syndrome associated with plagiocephaly were of 4 cases, and the other 8 cases were of fixed pelvic obliquity. 3. As for clinical symptoms and signs, apparent leg shortening was found in 12 cases(100 %), abduction limitations of the hip were in 12 cases(100%), external rotation contractures were in 6 cases(50%), and asymmetric gluteal folds were in 5 cases(41.2%). 4. On the plain X-rays, 5 cases(41.2%) were interpreted as congenital dislocation of the hip.Sclerosis of the acetabulsr margin was noticed in 3 csses(25%). 5. All cases were treated with Bryasnt traction, arthrography under general anesthesia to verify hip status and adductor tenotomy. And then von Rosen type abduction splint was applied for 8.5 weeks in average. 6. After 1 yesr 8 months follow up in average, all patient have ended up with excellent results regarding function and quality of hip development.