Women with non-ST-elevation acute coronary syndromes (NSTACSs) may have better outcomes than men, but the effect of NSTACSs in women undergoing percutaneous coronary intervention (PCI) has not been examined. We performed a prospective, multicenter, cohort study of consecutive patients who underwent PCI for NSTACS and stable angina during 3 National Heart, Lung, and Blood Institute Dynamic Registry recruitment waves (1997 to 2002) to examine the effect of female gender on adverse clinical events after PCI or stable angina for NSTACS. The primary end point was the combined rate of death, myocardial infarction, or rehospitalization for cardiac causes at 1 year. Compared with men with NSTACS (n = 2,124), women (n = 1,338) were older and more often had hypertension, diabetes mellitus, and history of heart failure (p <0.001 for all), whereas multivessel disease was less frequent (p <0.01). Procedural success and in-hospital adverse event rates were similar. Women with NSTACS had the highest 1-year rate of death/myocardial infarction/cardiac rehospitalization compared with women with stable angina pectoris (n = 462) or men (n = 995; women with NSTACS 37.6%, men with NSTACS 29.8%, women with stable angina 29.4%, men with stable angina 27.7%, p <0.001). The higher rate remained after adjustment for differences in baseline characteristics (adjusted hazard ratio 1.37, 95% confidence interval 1.20 to 1.56). Among women, NSTACS conferred a significantly higher risk for adverse events compared with stable angina (adjusted hazard ratio 1.41, p = 0.001), whereas the risk of adverse events was not different in men (adjusted hazard ratio 1.05, p = 0.5). In conclusion, women undergoing PCI for NSTACS have a higher risk of major adverse cardiac events than men or women undergoing PCI for stable angina.