An accepted method of measuring exercise tolerance was applied exclusively to geriatric practice for the purpose of exercise prescription. This stress testing was performed to minimize the risks of introducing exercise in an elderly population, and to restore or maintain elderly persons at their own optimal level of function, for life. As no geriatric testing protocol was available, two standardized protocols were chiefly used to start the trial program in March, 1978. A geriatric modification devised by the author is described. During the first month of the study, in a physician's office, ECG-monitored treadmill testing was conducted without mishap in 175 patients (age range, 60--89 years). All but 4 of the subjects (98 percent) led habitually sedentary lives, and documented coronary heart disease was present in about one-fourth of the series. The initial test data in this proposed continuing study are summarized. The methods for candidate selection, the safety precautions, and the test procedure are outlined. The distinction is made between testing by functional grades and testing to maximal levels. Information obtained from this stress test is an integral part of the individualized exercise prescription for each geriatric subject.