Persons hospitalized with heart disease were licensed as often in the pre-hospital period and drove slightly (but not significantly) fewer miles than did healthier persons of similar age, sex and neighborhood. After discharge, those who returned to driving reduced their mileage and drove under different conditions. This occurred both because of overall changes in life style (e.g. retirement) associated with illness and because of health effects on driving per se. In fact, while activities changed, the methods of transportation used to accomplish these remained the same, with driving oneself being the preferred mode. Physicians advised patients only about driving during the immediate recovery period rather than with an eye toward long-term safety risk. Few people reported their heart condition to the Department of Motor Vehicles. A functional severity score based on primary and comorbid conditions was developed to distinguish individuals with different amounts of impairment relevent to driving.