We describe the management of femoral agenesis in a young adult. Following previous treatment, including limb lengthening by the Ilizarov technique, the patient was left with 30 cm of shortening, a hip fused in abduction and external rotation, an ankylosed knee and an ankle which had been surgically fused. We decided to create a mono-segmental stump, based on a mobile hip, in order to accommodate a suitable prosthesis. Replacement arthroplasty of the hip was first undertaken using a femoral component with a long stem which crossed the knee into the upper tibia. This allowed correction of the rotational deformity and fusion of the knee in an appropriate position. Amputation above the ankle was then carried out under the same anaesthetic. A suction prosthesis was attached to the stump. The arthrodesis of the hip was the principle factor in deciding on this procedure rather than a Van Ness operation or further lengthening. The result at 3 years is satisfactory and the patient has good mobility.