In view of the widespread use of the axillary crutches as a temporary ambulatory device, and in some cases almost as a permanent rehabilitative measure, an objective evaluation of the performance level of leg amputees using axillary crutches was undertaken. Ten unilateral leg amputees constituting the test group were made to perform sitting, standing, level walking and stair ascending activities during which their energy expenditures, oxygen consumption, pulmonary ventilations and peak heart rates were measured by standard physiological procedures. The test group results were compared with the corresponding results of a control group, made-up of sixteen adult, healthy, able-bodied persons having sedentary habits. The metabolic costs of using axillary crutches were found to be unusually high in comparison with the normal standards: t tests performed clearly indicated the differences existing between the two groups for most of the test activities. The extra energy and effort required by the crutch-using unilateral amputee for the performance of standard activities of daily living and working contra-indicated the permanent use of axillary crutches. For temporary use also, the period of use should be reduced to the minimum. The information generated by this study may be used for comparison with the performance standards of other alternative handicapped-appliance systems and will be of value in the treatment, training and reablement assessment of the lower extremity handicapped. © 1974 Taylor & Francis Group, LLC.