The role of hepatitis E (HE) in sporadic morbidity at an endemic territory (Southern Uzbekistan) and the incidence of anti-HEV in different populations of a nonendemic region (Russia) were evaluated. Antibodies to HEV were detected in 22.1% of patients with acute HE, including mixed infections (+ HA or HB), in the Dekhkanabad district of Kashkadarya region in 1993. The estimated incidence of acute HE was 51.7 per 100,000 population. Analysis of monthly incidence of acute HE demonstrated a seasonal pattern of the morbidity: more than 80% of total recorded cases occurred in August-September. These data indicate the presence of group HEV infections and an important role of this infection in the structure of acute viral hepatitis at the endemic territory. Anti-HEV were found in some population groups at a nonendemic territory: in free-of-charge blood donors in Surgut (4%), in patients with HIV infection (1.6%), and in medical workers in Moscow (1.1%).