Hostility can predict coronary heart disease (CHD) and total mortality in men. However, in women this association has not been as thoroughly explored. This study examines whether hostile and aggressive attitudes are associated with myocardial infarction (MI) in postmenopausal women. Cases included 277 women who presented with an incident MI. Controls included a random sample of 988 female health maintenance organization enrollees. Women were asked the Hostile-Affect and the Aggressive-Responding factors of the Cook-Medley Hostility Scale. The Hostile-Affect score was linearly associated with increased risk for MI (odds ratio [OR] per point = 1.22; 95% confidence interval [CI95%] = 1.07-1.38), whereas the Aggressive-Responding score had a modest protective effect (OR = 0.92 per point; CI95% = 0.84-1.02); p = 0.009. Adjustment for sociodemographic and MI risk factors altered these results only slightly. These hostility measures are easily administered, and could help to identify women who are at high risk for CHD and who may benefit from preventive measures.