This paper describes the design, manufacture and use of a new prosthesis which produced reciprocating gait for a bilateral hip disarticulation amputee. A special mechanism used the hip extension moment during weight bearing to drive the contralateral limb through the swing phase. The user rapidly attained efficient and safe reciprocating gait, together with simple donning and doffing. The success of this project has major implications for hip disarticulation amputees in terms of profound improvements of their independence and self-esteem.