The Total-Condylar knee prosthesis is a non-hinged, semi-restricted prosthesis with partial intrinsic stability, incorporating a prosthetic surface covering the patella. The surgical technique involved includes release of the contracted soft tissues, so as to obtain symmetry and balance of the ligaments before the bone is cut. These bone cuts are made at a right angle to one another and are standardised. The cases presented comprise forty-eight knees (in forty-one patients), of whom thirty-eight were affected by arthrosis and ten by rheumatoid arthritis. The mean age of the patients was sixty-five years. They were examined not less than twenty-four months nor more than seventy months after operation. This was a prospective survey and the cases were consecutive. Excellent or good results were obtained in 89.5 per cent of cases. Only one case had to undergo re-operation, due to loosening of the tibial component, not to deep infection. The results were permanent over the review period, and the quality was as good as in prostheses of the hip.