Between May 1975 and December 1979, 113 patients had 153 arthroplasties using a total condylar knee prosthesis. Thirty patients (forty-two knees) died, and one (two knees) was lost to follow-up. Thirty-eight of these forty-four knees had been followed for more than two years, and none had had a revision. The remaining eighty-two patients (109 knees) were followed for an average of nine years (range, seven to 11.5 years). At the time of the latest examination, ten had had a revision for various reasons. For the ninety-nine knees that had the original prosthesis, the findings were compared with those of an evaluation that had been done four years postoperatively. The average over-all knee score was found to have decreased between the four-year and the latest follow-up evaluation, primarily because of a 7-point decrease in the score for function. The rate of infection was 0.6 per cent. The knees that had had patellar resurfacing had better over-all scores and better scores for pain than those that had not. This was particularly true in the patients who had osteoarthritis. The results of arthroplasty using a total condylar prosthesis appeared to be consistent and durable. Although there was a decrease in the quality of the functional result with increasing age, the patients reported consistent relief of pain.