Morquio-Brailsford's disease belongs to the mucopolysaccharidoses, it shows growth-retarding with dysproportional dwarfism. Due to bone deformations and joint dysplasias very early severe arthritic changes arise with serious functional disabilities, especially in the loaded lower extremities; this may lead to early alloplastic joint replacement surgery. By means of two patients with respective bilateral THR and singular total knee replacement intraoperative complications and postoperative follow up (up to 12 years) are represented casuistically. Unfavourable anatomic properties (dysplasia, size of joints) were the main technical surgery problem; the use of individually manufactured implants might be recommended in some of these cases. The achieved subjective and objective functional results of our cases were-compared to the preoperative situation-altogether quite satisfactory.