Analysis of 1150 post-infarct and post-aorto-coronary bypass graft patients referred to the Toronto Rehabilitation Centre revealed that approximately 10% have not returned to work six months after the acute event. White-collar workers are more successful than blue-collar workers in resuming work, as are those medically treated as compared with the surgically treated. The reasons for prolonged unemployment were more frequently non-medical than medical. Detailed assessment is required where there is doubt about the patient's work capacity, or where legislation and/or trade practices demand it. The simplest procedure is an exercise test with energy cost matching. Telemetry during simulated work tasks or while on work stations in the Centre allows more flexibility, with actual observation and telemetry on the job site the only recourse in certain situations.