Patients with hip disarticulation (HD) require high energy expenditure for successful prosthetic ambulation. Thus, older patients are rarely fitted with an HD prosthesis. To our knowledge there are no reports of gait analysis following successful prosthetic fitting of an elderly HD amputee patient with systemic cardiopulmonary disease. We report the case of successful prosthetic ambulation in a 73-year-old man with HD secondary to histiosarcoma and a medical history significant for stable angina, chronic obstructive pulmonary disease, and diabetes mellitus. The patient underwent gait training with an endoskeletal prosthesis and achieved ambulation to 400 feet with bilateral forearm crutches. Vicon kinematic gait analysis revealed a cadence of 44 steps/min (112 steps/min normal), and double support time of 47% (26% normal). Oxygen rate during ambulation (VO2) was 11.0 mL/kg/min at velocity of .35 m/sec, compared with published figures for ambulation in those with HD of 10.73 mL/kg/min at velocity of .93 m/sec. At 1-year follow-up, the patient continued to walk into church with the prosthesis. We conclude that a trial fitting of an HD prosthesis should be considered on an individual basis in elderly amputee patients.