Epidemiologic research has increasingly implicated psychological factors in the emergence of atherosclerotic coronary heart disease in human beings. The study of behavioral influences on atherogenesis in man, however, is impeded by the difficulty of assessing coronary artery atherosclerosis in asymptomatic individuals and by the fact that significant arterial lesions typically develop only over relatively protracted intervals. Consequently, we have recently attempted development of an appropriate animal model for examining the atherogenic effects of psychosocial variables. In the first of two investigations, an experimental stressor--involving repeated reorganization of socially housed groups of adult, male cynomolgus monkeys (Macaca fascicularis) fed a moderately atherogenic diet--resulted in increased coronary artery atherosclerosis relative to control animals, though only among monkeys which retained dominant social status over the 22 months of the study. In the second investigation, which employed the same experimental procedures among monkeys fed a low cholesterol/low saturated fat diet, periodic social group reorganization similarly led to development of greater atherosclerosis in the coronary arteries. In neither experiment were psychosocial influences on coronary atherogenesis attributable to the concomitant effects of other physiologic variables commonly associated with atherosclerosis (e.g., serum lipids, blood pressure).