: Multiple displacement patterns, stride dimensions, and temporal components during slow, free-speed, and fast walking were compared in the same seven above-knee amputees using prostheses with constant-friction knee components and using hydraulic swing-control knee components. During walking with the hydraulic-type prostheses, the amputees showed a wider range of walking speeds, improvement in the equality of the durations of successive swing and stance phases, and greater uniformity of forward progression. Improvements toward normal were also seen in several of the displacement patterns of the prosthetic limb during walking with the hydraulic knee. Several gait abnormalities persisted with both types of prostheses.