Heart failure is a significant public health problem. The epidemiology and practice pattern of emergency department (ED) visits for acute decompensated heart failure (ADHF) have not been well characterized. A better description is essential to highlight areas in which improvements or additional research are needed. We analyzed all ED visits for ADHF of patients>or=40 years old using the data of the National Hospital Ambulatory Medical Care Survey from 1992 to 2001. During this 10-year period, an estimated 10.5 million ED visits occurred for ADHF, representing 2.9% of all ED visits. The number of ADHF visits increased on average by 18,500 per year, for a 19.4% absolute increase during the decade. The rate per 1,000 United States population was unchanged. The average patient was 74 years old, and patients>or=65 years accounted for 79% of visits. Loop diuretics were administered in 63% and vasodilators in 29% of visits. The ED visit rate per 1,000 United States population was 53% higher in blacks than in whites (14.2 vs 9.3). In a multivariate model, white race was a significant predictor of hospitalization. In conclusion, during the past decade, the absolute number of ED visits for ADHF has increased owing to the aging population. Diuretics remain the most common treatment. Race-related differences in hospitalization merit additional study.