The present correlational study compared behavioral and psychophysiological characteristics of coronary patients who were either medicated or not medicated with the beta-adrenergic blocking drug propranolol. Eighty-eight patients were given a structured Type A interview (SI) and a history quiz while heart rate and blood pressure were monitored. Data were analyzed controlling for age, sex, extent of coronary artery disease, and history of angina. Results indicated that patients taking propranolol (n = 65) were significantly lower in intensity of Type A behavior than patients not taking propranolol (n = 23). No effects were obtained for patients medicated or not medicated with diuretics, nitrates, or other CNS active drugs. Propranolol patients also showed lesser heart rate and rate-pressure product responses to the interview, but did not differ in blood pressure responses. Components of Type A which were lower in propranolol patients included speech stylistics (loud/explosive, rapid/accelerated, potential for hostility). Content of responses to the SI and scores on the Jenkins Activity Survey did not differ between the groups. An explanation for these results is offered in terms of the effects of propranolol on peripheral sympathetic responses, and evidence for a physiological substrate for Type A behavior. A conceptualization of the Type A pattern in terms of cognitive and physiological components is advanced, and implications for clinical intervention are discussed.