To assess gender-based differences in presentation and outcome after non-ST-elevation myocardial infarction (NSTEMI) in clinical practice, this study examined data from the Acute Coronary Syndrome registry, which enrolled 16,817 patients from 2000 through the end of 2002, 6,358 of them with NSTEMIs (34.1% women). Women with NSTEMIs were 7.5 years older, had a history of myocardial infarction and percutaneous coronary intervention or coronary artery bypass graft less often, and were less likely to have smoked. They more often had a history of systemic hypertension and diabetes mellitus, but this difference was due to their older age. Reperfusion therapy was performed less often in women, which still was significant after adjustment for baseline variables (odds ratio 0.71, 95% confidence interval 0.63 to 0.80). Clopidogrel was given less often in women (43.4% vs 56%). After adjustment for age, gender differences in medical therapy with statins, aspirin, and beta blockers were not significant. Hospital mortality was 1.7 times greater in women. This difference was not significant after adjustment for age (odds ratio 1.07, 95% confidence interval 0.84 to 1.35). Women had greater crude long-term mortality, but after age adjustment, this difference was no longer significant (odds ratio 0.92, 95% confidence interval 0.76 to 1.11). In conclusion, women with NSTEMIs were older than men and thus more often had concomitant diseases but less often had a history of myocardial infarction or coronary artery bypass grafts. They less often received acute percutaneous coronary intervention and less often were treated with clopidogrel. However, there was no difference in age-adjusted mortality in women.