CONTEXT: Although an invasive strategy is frequently used in patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS), data from some trials suggest that this strategy may not benefit women. OBJECTIVE: To conduct a meta-analysis of randomized trials to compare the effects of an invasive vs conservative strategy in women and men with NSTE ACS. DATA SOURCES: Trials were identified through a computerized literature search of the MEDLINE and Cochrane databases (1970-April 2008) using the search terms invasive strategy, conservative strategy, selective invasive strategy, acute coronary syndromes, non-ST-elevation myocardial infarction, and unstable angina. STUDY SELECTION: Randomized clinical trials comparing an invasive vs conservative treatment strategy in patients with NSTE ACS. DATA EXTRACTION: The principal investigators for each trial provided the sex-specific incidences of death, myocardial infarction (MI), and rehospitalization with ACS through 12 months of follow-up. DATA SYNTHESIS: Data were combined across 8 trials (3075 women and 7075 men). The odds ratio (OR) for the composite of death, MI, or ACS for invasive vs conservative strategy in women was 0.81 (95% confidence interval [CI], 0.65-1.01; 21.1% vs 25.0%) and in men was 0.73 (95% CI, 0.55-0.98; 21.2% vs 26.3%) without significant heterogeneity between sexes (P for interaction = .26). Among biomarker-positive women, an invasive strategy was associated with a 33% lower odds of death, MI, or ACS (OR, 0.67; 95% CI, 0.50-0.88) and a nonsignificant 23% lower odds of death or MI (OR, 0.77; 95% CI, 0.47-1.25). In contrast, an invasive strategy was not associated with a significant reduction in the triple composite end point in biomarker-negative women (OR, 0.94; 95% CI, 0.61-1.44; P for interaction = .36) and was associated with a nonsignificant 35% higher odds of death or MI (OR, 1.35; 95% CI, 0.78-2.35; P for interaction = .08). Among men, the OR for death, MI, or ACS was 0.56 (95% CI, 0.46-0.67) if biomarker-positive and 0.72 (95% CI, 0.51-1.01) if biomarker-negative (P for interaction = .09). CONCLUSIONS: In NSTE ACS, an invasive strategy has a comparable benefit in men and high-risk women for reducing the composite end point of death, MI, or rehospitalization with ACS. In contrast, our data provide evidence supporting the new guideline recommendation for a conservative strategy in low-risk women.