The conventional total contact suction AK prosthesis presents several disadvantages, such as difficulty in wearing the socket in a sitting position, difficulty in obtaining a favourable disposition of the stump soft tissues in the socket and difficulty in avoiding stump perspiration problems. In an attempt to solve these disadvantages, a new AK prosthesis with a thermoplastic double socket was developed at the Tokyo Metropolitan Rehabilitation Center for the Physically and Mentally Handicapped. The double socket is composed of an external socket attached to the lower parts and a detachable internal socket, and appears to solve all the disadvantages of the conventional prosthesis. This prosthesis is called the TC prosthesis, and abbreviation for the Tokyo Metropolitan Rehabilitation Center. The first model of this prosthesis, (TC-1) has a metal valve. A new rubber sheet valve was developed to solve several disadvantages of the metal valve in the TC-2 prosthesis. Since November 1978 the TC-1 has been fitted to 295 AK amputees, including 9 bilateral AK amputees, and since March 1980, 145 AK amputees have received the TC-2, including 6 bilateral amputees. Satisfactory results have been obtained with both prostheses.