In 98 infants at the age of 3-4 months acetabular dysplasia without decentration was diagnosed by means of combined method of Schultheiss/wedge-shaped segments/ and Doberti and Manhood/acetabular defects/. This method was confronted with the classical procedure using measurements of acetabular index and with other radiological and clinical signs. It is concluded that the only reliable sign of acetabular dysplasia at the age of 3-4 months is the disturbance of ossification at the end of the acetabular roof in the sense of partial or total defects. All other radiological as well as clinical signs including acetabular index values, asymmetry of gluteal folds and limitation of abduction in the hip joints are shown to be of little or no importance.