This study presents a review of the epidemiology of status epilepticus (SE) in Richmond, Virginia, U.S.A. The data summarize some of the first population-based information on the natural presentation of SE in a controlled community setting. SE occurred with an absolute incidence rate of 41 patients per 100,000 residents per year in Richmond. The frequency of total SE occurrences was 50 patients per 100,000 residents per year. Overall mortality in this population was 22%. Absolute incidence and occurrences of SE in this population were shown to be underestimates due to the inability, for multiple reasons, to document all cases of SE. Based on the Richmond data, the number of SE cases, frequencies of occurrence, and deaths per year occurring in the United States were estimated to be 102,000-152,000, 125,000-195,000, and 22,000-42,000, respectively. In Richmond, nonwhites had a much higher incidence of SE than did whites. Partial SE was the most common form of seizure initiating SE. Age and etiology were also found to contribute to mortality. Infants <1 year of age had the highest incidence of SE, but the elderly population represented the largest number of SE cases. This study provides a review of the first prospective, population-based, epidemiological data on SE and shows that SE is a major medical and neurological emergency in both academic and community hospital settings.