The authors have developed their own classification of the deformities of labrum glenoidale in congenital hip dislocation. Open reposition was performed by the Ludloff procedure. The basic material for their work was the group of patients operated on at I. Orthopaedic Clinic of the Faculty of General Medicine of Charles University in Prague in the years 1970-1985. In the course of this period they operated on 78 hip joints in 70 children, out of which 8 operations were bilateral, the group comprised 17 boys and 53 girls, operation was performed on 30 right hip joints and 48 left ones. The age of children ranged from 5 to 23 months. The average age of children in time of operation was 9.3 months. On the basis of the cadaver material the authors have found out that glenoidale represents an extensive part of acetabulum. Labrum glenoidale is considerably more sizable in the dorsal parts of acetabulum so that the head seems to be completely enveloped by ligamentary limbus and the acetabulum seems to form at least half of the ball-shaped surface. In the dorsal and upper parts the acetabulum is from great part formed by a fibrous structure which is easily deformed. The pressure applied to the head dorsally can result in its dislocation just because the cartilaginous model of acetabulum is flat in its dorsal and proximal parts. This easily deformable structure is under certain conditions deformed by pressure of the head in such a way that in the first phase in the course of the onset of the dislocation it is always everted and in the second phase the evertion lither persists or the head shifts over the margin of the limbus and the limbus is then inverted by reposition force. The authors present in their work the classification of the limbus. Proceeding from operation findings they divide limbi into four groups according to differences in their shape: Type I: regularly annular (everted) limbus--it corresponds to a normal anatomic shape, it is not pronouncedly deformed and does not present an impediment to reduction. Type II: inverted gracilis limbus--it is exaggerated in comparison to the normal one, usually it is inverted in the acetabulum, it is never rigid but elastic. Together with the structure of capsule it can be an impediment to reduction. It can be relatively easily everted. Type III: inverted callous limbus--it is sizable, rigid, reducing by its position the capacity of the acetabulum. The reduction is usually difficult.(ABSTRACT TRUNCATED AT 400 WORDS)