Data from the Commission on Professional and Hospital Activities, Professional Activities Study were used to estimate the incidence and geographic distribution of hospitalized patients with toxic shock syndrome (TSS) in the United States in 1981 and 1982. There were 1004 discharges with a diagnosis of TSS from hospitals participating in the study. These discharges could not be validated using clinical criteria. Using these data, the projected incidences for the United States were 0.78/100,000 and 0.84/100,000 total population in 1981 and 1982, respectively. Female patients, 15 to 19 years of age, had the highest age-specific incidence (4.8/100,000). Race, sex, and geographic distributions of cases reported to the national surveillance system were similar to those of patients discharged with a diagnosis of TSS from hospitals participating in the study.