Ankle arthrodesis has been regarded as a good operative treatment for post traumatic and rheumatoid arthritis of ankle, and ankle arthroplasty has been also developed with several types, from 1970, by Lord & Marotte. Ankle arthroplasty is more functional & less cosmetic troublesome than arthrodesis, and with more developed prosthesis design, more good result will come. The authors operated 6 cases of total ankle arthroplasty for posttraumatic and rheumatoid arthritis of ankle, which were also indications of arthrodesis, and introduce the results and operative problems of ankle arthroplasty.