The authors retrospectively reviewed 29 hip and 13 knee arthroplasties performed in 17 adolescents and young adults from 1973 through 1979. Most patients had severe multiple joint involvement; 16 had juvenile rheumatoid arthritis. Clinical and roentgenographic evaluations were performed before operation and at routine intervals for up to 11 years after operation. The average final follow-up evaluation was at ten years seven months. The modified Harris rating improved from 17 before operation to 68 at final evaluation. A dramatic improvement was noted in the ambulatory ability of 13 patients in whom increased joint motion and reduced deformity was observed at follow-up evaluation. At the 11-year roentgenographic review, 32% of hips had gross loosening, and an additional 39% had radiolucent lines greater than 2 mm in thickness in more than two radiographic zones. No lucency greater than 2 mm was noted in any of the knee replacements. Complications included one immediate collapse of the medial tibial plateau, four femoral fractures, one hip dislocation, and one case of arthrofibrosis. Despite untoward roentgenographic results and the high incidence of complications, total arthroplasty has dramatically improved the quality of life for these patients with multiple joint pathology. For this reason, the authors continue to recommend joint replacement in these individuals and the use of new prosthetic designs and surgical techniques.