During the past 2 decades, randomized trials have proved the efficacy of several treatments for non-ST-elevation acute coronary syndromes (NSTE-ACSs), including aspirin, β blockers, and coronary revascularization. However, the cumulative effectiveness of these evolving therapies in actual clinical practice remains unknown. The Atherosclerosis Risk In Communities (ARIC) surveillance study uses rigorous prospective community surveillance to monitor the epidemiology of coronary heart disease among subjects who are 35 to 74 years of age and reside in 4 United States communities, with a population totaling 370,000 subjects. We identified 6,379 ARIC surveillance patients who were hospitalized with NSTE-ACS (defined as cardiac chest pain and ST depression or T-wave inversion on the presenting electrocardiogram) between 1987 and 2000 and then analyzed 30-day and 1-year mortalities by calendar year of admission. Using logistic regression, 30-day mortality was modeled first using predictor variables of the calendar year, ARIC community, and indicators of severity and co-morbidity and then by adding variables for treatment with aspirin, β blockers, and coronary revascularization to this model. Crude 30-day mortality decreased from 8.6% in 1988 to 3.6% in 2000 (p for trend <0.001), a trend that remained significant (p = 0.006) after adjustment for case severity and co-morbidity. The trend became nonsignificant after adjustment for treatment variables, suggesting that newer treatments may explain the improved survival. In conclusion, 30-day mortality from NSTE-ACS has decreased as treatment has improved.