Recombinant alpha 2c-interferon was administered to 12 consecutive patients with fulminant viral hepatitis. The disease was caused by coinfection by HBV and HDV in seven patients, by HDV superinfection of a chronic HBV carrier in two, by HBV alone in two and by HAV in one. Eight patients were drug addicts. Interferon administration was initiated shortly after the onset of hepatic encephalopathy and no patient was in grade IV coma at the beginning of therapy. Ten patients died and only two survived. One of the survivors was an asymptomatic HBV carrier superinfected by HDV in whom treatment with interferon for 3 months did not prevent the development of chronic delta infection and liver cirrhosis. These results show that alpha 2c-interferon does not have significant therapeutic value in fulminant viral hepatitis, particularly if it is caused by HDV.