1 500 infants have been examined by two orthopaedic surgeons within forty eight hours. The examination of the feet has showed that the usual position in utero was the dorsiflexion. A new classification of deformities of the feet is proposed. The examination of the knees has permitted to discover a rotatory instability between the femur and the tibia in 2% of the infants. Some of them were actual dislocations. During the examination of the hips, it has been researched an instability; the passive abduction, the tension of the adductors and an abduction contracture have been analysed. Some instable hips are easy to detect because there is a jerk (ressaut) but others are very difficult because there is no snapping sign but only a telescoping displacement (piston). The rate of unstable hips was 1.7%. As the combination of an unstable hip and an adductor hypertonicity is usual it is very important to detect a pelvic obliquity and a bilateral adductor-hypertonicity. The various forms of normal birth postures and the relation to orthopaedic deformities of the inferior limbs are studied.