purpose: Description of the epidemiology, morbidity, and mortality of hospitalized adults with typical measles. patients and methods: Restrospective case analysis of 33 adults who required acute care for complications of measles in a public hospital in Los Angeles, California. The diagnosis of measles was established on standard clinical or serologic grounds. results: Of 68 patients (age greater than 14) with signs and symptoms of measles who presented for medical care, 33 (19 males and 14 females) required hospitalization; 18 were natives of the United States. The patient age was 26.1 ± 7.3 (mean ± SD) years; four patients, all natives of the U.S., were born before 1957. The duration of hospitalization was 6.8 ± 8.8 days for all patients and 13.4 ± 14.2 days for the nine patients who required intensive care unit (ICU) care. Six of the ICU patients required mechanical ventilation for 11.0 ± 15.0 days; two deaths occurred among these patients. During the course of their illness, 7 of 25 (28%), 11 of 28 (39%), 6 of 28 (21%), and 5 of 16 patients (31%) had peak lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, and creatine kinase values, respectively, that were greater than 5 times the upper limit of normal. Fifteen of 28 patients (54%) developed total serum calcium levels less than or equal to 2.0 mmol/L. Ten cases were serologically confirmed; 23 cases were diagnosed as probable measles on clinical grounds. There were no significant demographic, clinical, or laboratory differences between patients with confirmed and probable measles. No patients had characteristic manifestations of atypical measles. The sole immunocompromised patient died. conclusions: Measles in adults may result in severe, life-threatening complications that utilize substantial medical resources. Physicians need to appreciate the clinical presentations and manifestations of severe measles in adults and to provide measles vaccine to nonimmune adults during community-wide outbreaks.