Energy expenditure was measured using a metabolic measurement cart (MMC) for 8 patients with hip disarticulation (HD, group 1), 10 patients with hemipelvectomy (hp, group 2), and 11 able-bodied subjects (group 3). Velocity and O2 consumption of comfortable, fast, and slow walking speeds were measured with a MMC. Comfortable walking speeds with HD and hp were 51% to 61% of controls (p less than 0.001), but there was no difference in O2 uptake per minute among the three groups. Fast walking speeds for groups 1 and 2 was 70% to 75% of comfortable walking speeds in group 3 (p less than 0.01), and the mean O2 uptake of fast walking speeds in groups 1 and 2 was 40% to 50% more than that of group 3 at comfortable speeds. Energy cost per unit distance (work) was 80% to 125% greater with patient groups than with able-bodied subjects. The difference between the pre- and immediate postexercise pulse rates for comfortable walking speeds were higher in groups 1 and 2 than in group 3.