Gender-related differences in outcome after myocardial infarction may relate to biased treatment allocation. To address this concern we analyzed 573 patients presenting with ST-segment elevation acute myocardial infarction (AMI), and treated within 6 hours with reperfusion therapy. Two-hundred eighty patients (49%) received direct coronary angioplasty, whereas 293 (51%) received thrombolytics followed by angioplasty (p = NS). Seventy-four percent were men and 26% were women (p = NS for differences in sex distribution between the 2 treatment groups). Women were older in both groups (p < 0.01). Inferior AMI was seen more often in women (64% of direct angioplasty, 71% of lytic first) than in men (51% and 59%, respectively; p < 0.03). There was no gender-related differences in presence of multivessel coronary artery disease, prior AMI, prior bypass surgery, baseline ejection fraction, percentage of patients with ejection fraction < or = 40%, number of narrowings dilated, or angioplasty success. Patients who underwent direct angioplasty had more multivessel disease (p < 0.001) and prior coronary artery bypass surgery (p = 0.002). After a mean follow-up of 129 +/- 113 weeks, no gender-related differences were seen in the need for cardiac catheterization, documented restenosis, AMI, coronary artery bypass surgery, clinical ischemia, or death. Patients treated with direct angioplasty were more likely to undergo coronary artery bypass surgery (p < 0.05) or to die (p < 0.01). Thus, women undergoing reperfusion therapy for ST-segment elevation were older than men, with a higher frequency of inferior wall AMI. No specific gender-related bias in treatment allocation was evident.