At Orthopedic Department of Kyung Hee University Hospital, we performed 20 total knee replacements in 12 patients who had rheumatoid arthritis and 18 total knee replacements in 13 patients who had osteoarthritis during the period from August 1982 to May 1986. All patients were female. Comparative analysis was done between the two groups with a follow-up period ranging from 1 year to 4 years 8 months, average being 2 years and 3 months. The average age of rheumatoid arthritis patients was 10 years younger than osteoarthritis patients. The improvement of range of knee motion after total knee replacement was greater in rheumatoid arthritis comparing to osteoarthritis. Preoperative flexion contracture was more severe in rheumatoid arthritis than osteoarthritis, but after total knee replacement the average degree of flexion conrcacture was no significant difference between two groups. The average of preoperative Hospital Surgery Knee Rating Scale was low in rheumatoid arthritis group than in osteoarthritis group, but postoperative Knee Rating Scale was similar in both groups. It seems that the problem of wound was more frequent in rheumatoid arthritis than in osteoarthritis.