PIP: A male to female ration of coronary disease of 2:1 has been a consistent finding. This differential persists event when the classic risk factors for coronary disease--hypertension, smoking, obesity, diabetes, and hyperlipidemia--are controlled for gender. The most likely ultimate cause of this phenomenon is male-female differences in sex hormone patterns. Clinical studies in this area have either compared the sex hormone profiles of men and women with and without coronary disease or computed the relative prevalence of disease in populations that differ in their sex hormone patterns. In general, research findings have disputed the hypothesis that persons with coronary disease have low levels of a protective factor such as estrogen or progesterone and high levels of testosterone. Coronary disease patients actually have elevated estrogen levels and low testosterone levels; endogenous progesterone levels are normal before infarction but show a stress-mediated increase in the immediate postinfarction period. Findings of a low prevalence of coronary disease in premenopausal women, a loss of protection after menopause, and a low prevalence of coronary disease in men with cirrhosis-related hyperestrogenemia suggest that natural estrogens are antiatherogenic. The protective effect of pregnancy against myocardial infarction, despite concomitant potentially thrombogenic levels of estrogen at the time, seems to indicate that progesterone, whose levels are also extremely high during pregnancy, plays a major anti-infarction protective effect distinct from that of estrogen. Studies of women oral contraceptive (OC) users and men taking estrogens for brief periods have found that these exogenous hormones produce coronary thrombosis but not atherosclerosis. Finally, the finding of increased coronary disease risk in long-term OC users indicates that synthetic estrogens favor coronary atherosclerosis by suppressing natural estrogen and progesterone production.