To determine recent trends in rates of hospitalization, mortality, and hospital case fatality for severe sepsis in the United States. Trend analysis for the period from 1993 to 2003. U.S. community hospitals from the Nationwide Inpatient Sample that is a 20% stratified sample of all U.S. community hospitals. Subjects of any age with sepsis including severe sepsis who were hospitalized in the United States during the study period. None. Utilizing International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for septicemia and major organ dysfunction, we identified 8,403,766 patients with sepsis, including 2,857,476 patients with severe sepsis, who were hospitalized in the United States from 1993 to 2003. The percentage of severe sepsis cases among all sepsis cases increased continuously from 25.6% in 1993 to 43.8% in 2003 (p < .001). Age-adjusted rate of hospitalization for severe sepsis grew from 66.8 +/- 0.16 to 132.0 +/- 0.21 per 100,000 population (p < .001). Age-adjusted, population-based mortality rate within these years increased from 30.3 +/- 0.11 to 49.7 +/- 0.13 per 100,000 population (p < .001), whereas hospital case fatality rate fell from 45.8% +/- 0.17% to 37.8% +/- 0.10% (p < .001). During each study year, the rates of hospitalization, mortality, and case fatality increased with age. Hospitalization and mortality rates in males exceeded those in females, but case fatality rate was greater in females. From 1993 to 2003, age-adjusted rates for severe sepsis hospitalization and mortality increased annually by 8.2% (p < .001) and 5.6% (p < .001), respectively, whereas case fatality rate decreased by 1.4% (p < .001). The rate of severe sepsis hospitalization almost doubled during the 11-yr period studied and is considerably greater than has been previously predicted. Mortality from severe sepsis also increased significantly. However, case fatality rates decreased during the same study period.