BACKGROUND: It is unknown how anemia influences the invasive management of patients with non-ST-segment elevation myocardial infarction (NSTEMI) and associated mortality. We investigated whether receipt of cardiac catheterization relates to 6-month death rates among patients with different severity of anemia. METHODS: We used data from the population-based Worcester Heart Attack Study, which included 2634 patients hospitalized with confirmed NSTEMI, from three percutaneous coronary intervention-capable medical centers in the Worcester (Massachusetts, U.S.A.) metropolitan area, during five biennial periods between 1997 and 2005. Severity of anemia was categorized using admission hematocrit levels: less than or equal to 30.0% (moderate-to-severe anemia), 30.1-39.0% (mild anemia), and more than 39.0% (no anemia). Propensity matching and conditional logistic regression adjusting for hospital use of aspirin, heparin, and plavix compared 6-month postadmission all-cause mortality rates in relation to cardiac catheterization during NSTEMI hospitalization. RESULTS: Compared with patients without anemia, patients with anemia were less likely to undergo cardiac catheterization {adjusted odds ratio (AOR) 0.79 [95% confidence interval (CI): 0.67-0.95] for mild anemia and 0.45 (95% CI: 0.42-0.49) for moderate-to-severe anemia}. After propensity matching, cardiac catheterization was associated with lower 6-month death rates only in patients without anemia [AOR 0.26 (95% CI: 0.09-0.79)] but not in patients with mild anemia [AOR 0.55 (95% CI: 0.25-1.23)]. The small number of patients rendered data inconclusive for patients with moderate-to-severe anemia. CONCLUSION: Anemia at the time of hospitalization for NSTEMI was associated with lower utilization of cardiac catheterization. However, cardiac catheterization use was associated with a decreased risk of dying at 6 months after hospital admission only in patients without anemia.