OBJECTIVES To determine whether outcome differences based on the patient's sex occur after myocardial infarction (MI) at a large private hospital. STUDY DESIGN We conducted a large cohort study. POPULATION Inclusion required hospital admission between January 1, 1998, and June 30, 1999, and a diagnosis of acute MI or subendocardial infarction. The number of patients included in the study was 1669, Data were collected at discharge on age, sex, race, health insurance, hypercholesterolemia, diabetes, smoking, hypertension, and the extent of coronary artery disease. OUTCOMES MEASURED The 8 outcomes analyzed were angiogram, angioplasty, stent placement, coronary artery bypass grafting (CABG), mortality, time in the intensive care unit, total length of stay, and combined catherization procedures. RESULTS After adjusting for 7 confounding variables, we found no significant differences between men and women for mortality, ICU time, total hospital time, stent placement, angiogram, angioplasty, or combined catheterization procedures, Men had significantly more CABG (relative risk [RR] 1,96, P < .01), Among patients who underwent CABG (N = 204, men had significantly more 3-vessel coronary disease (RR 1.44, P <.01) and left main coronary artery disease greater than 50% v (RR 1.58 P <.01) Once we had controlled fur the extent of coronary artery disease, we found no difference between the sexes for CABG. CONCLUSIONS During hospitalization after an Nil, Most cardiovascular outcomes and process measures are the same for men and women. The greater frequency of CABG in men than in women is explained by men's greater frequency of 3-vessel and advanced left-main coronary disease.