The objective of this study is to investigate energy consumption during prosthetic walking and physical fitness in older hip disarticulation (HD) subjects and to examine the ambulatory outcome in a community setting. The subjects were seven unilateral HD amputees with an average age of 67.7 +/- 3.9 yr. Energy consumption was measured during prosthetic walking at each individual's comfortable walking speed (CWS) by means of a portable telemetric system. An incremental exercise test was performed to evaluate fitness. The average CWS for the subjects was 30.5 +/- 9.6 m/min. The average oxygen consumption rate at each CWS was 18.3 +/- 2.4 mL/kg/min, and the average oxygen cost was 0.639 +/- 0.165 mL/kg/m. The maximum oxygen uptake during exercise as a proportion of predicted maximum oxygen uptake (%VO2max) for the subjects was 57.2 +/- 11.1. Five subjects continued prosthetic walking on return to their communities. Two subjects abandoned prosthetic walking. The %VO2max for the five who continued prosthetic walking after discharge ranged from 55.8 to 72.0. The subjects who abandoned prosthetic walking had lower %VO2max of 43.3 and 44.2. Energy consumption during prosthetic walking at CWS seemed not to be excessive. Older HD amputees in good physical condition were able to successfully walk with a prosthesis in a community setting. A lower level of fitness appears to make community walking prohibitive.