Experience with total knee arthroplasty in the extremely elderly population, which has not been previously reported, is reviewed. Sixty-two total knee prostheses were implanted in 43 patients aged 80 to 95 years (average, 82 years). Ninety percent of the patients had a preoperative diagnosis of osteoarthritis. The results were compared with those obtained in a younger reference group (average age, 62 years) receiving 60 total knee prostheses.