Abstract. Forty-one patients with acute or fulminant hepatitis and 86 control patients were entered into a study of sporadic, acute, and fulminant hepatitis in the N'Djamena area of Chad in 1993. Acute hepatitis B was diagnosed in nine (22%) patients and acute hepatitis E in 27 (66%) patients. No acute hepatitis A was observed and 10% of the patients had serologic markers of hepatitis C virus (HCV) infection. Dual acute hepatitis B and E were observed in four patients (10%) and acute HEV infection was associated with chronic hepatitis B surface antigen carriage in 16 (39%). Epidemiologic findings concerning HBV from Chad suggest that these patients had undiagnosed chronic liver disease due to HBV, with acute deterioration caused by superimposed HEV replication. Moreover, it is obvious that in developing countries only the most severe cases of hepatitis are seen in hospital settings and a large proportion of them are related to superinfection with HBV and HEV. Antibody to HEV was observed in 22% of the control patients. This observation and the fact that epidemic and sporadic cases of HEV are observed in Chad indicates that HEV is highly endemic in this country.Hepatitis E virus (HEV) infection is generally easily recognized when the virus provokes epidemic outbreaks that are identified or suspected, predominantly in tropical and subtropical areas. The contamination of water supplies with HEV-positive feces appears to be responsible for these epidemics, whereas person-to-person transmission of the virus or food-borne spread have been rarely observed.