Total knee arthroplaty has been used to treat the elderly patient who has severe arthritis but the early designs were associated with many problems, which frequently led to early failure. In 1974, the total knee arthroplasty was introduced and the reported results of this operation have improved consistantly with time. Recently the good results has been shown to treat rheumatoid patients and osteoarthritis patients less than 45 years old patients. At the department of orthopaedic surgery of Kosin Medical College, between 1984 and 1988, total knee arthroplasty was performed in 17 patients (22 kness) who had rhematioid arthritis (7 patients) and osteoarthritis (11 patients), and had followed for an average of 1 year and 8 months. The results were as follows 1. The knee that had rheumatoid arthritis had better knee scores than that of osteoarthritis. 2. The knee that remained the post cruciate lig. had better range of motion than that sacrificed. 3. The knees that had not used cement had better knee scores than that had used the cement. 4. The knees that had patella resulrfacing had better scores for pain than that had not.