The energy used for walking with crutches and canes was determined by measuring oxygen consumption in ten normal subjects who used Lofstrand and axillary crutches with four different gaits. For all assisted gaits the self-selected velocity was less than that for normal walking and the energy used was greater than for normal walking. Use of each crutch type required the same amount of energy. Use of a cane or crutches with twqoint alternating and three-point partial-weight-bearing gaits required about 33 per cent more energy than normal walking. The swing-through and the three-point non-weight-bearing gaits required about 78 per cent more energy than normal walking. It is suggested that these energy requirements be considered when prescribing an assistive device.