Congenital dislocations of the knee (CDK) are rare, occurring 40-80 times more rarely than congenital dislocation of the hip (CDH). In a multicentric study of the European Paediatric Orthopaedic Society, 56 cases of CDK were found in 46 babies. Many other malformations associated with CDK were noticed, and muscular abnormality was always found at the knee. According to the classification of Leveuf, three grades have to be considered: grade 3, or complete dislocation, was the most frequent. At birth, treatment consisted of physiotherapy with rigid splint. Twenty-four patients with CDK have been treated only by the conservative technique. Operations were performed according to the abnormalities of the extensor apparatus: a progressive release and lengthening of the quadricipital tendon was necessary in all cases. In all forms of treatment, the range of the knee flexion was 120 degrees. Only two children had a bad result because of unstable knees. Results were always better with conservative treatment.