By routine screening for serologic markers of hepatitis A and B in patients with acute hepatitis, 30 chronic carriers of hepatitis B virus with serologic evidence of acute hepatitis A and two patients with simultaneous acute infection with hepatitis A virus and hepatitis B virus were detected.

For evaluation of clinical data, two major risk groups were distinguished. Nine patients were drug addicts and 17 were children and young adults from Mediterranean countries or southeast Asia.

During the acute phase of illness, serum bilirubin and SGPT levels did not differ from those in other patients with acute hepatitis A. In three patients for whom follow-up sera were available, HBsAg concentration decreased during the acute stage of hepatitis A.