Interferon-gamma (IFN-gamma) and prostaglandin E2 (PGE2) production was evaluated in cultured peripheral blood mononuclear cells taken from patients with type B acute viral hepatitis at the onset of symptoms, at 1st and 2nd week of disease, and from healthy controls. Concanavalin A-stimulated cells cultured for 24, 48 and 72h showed significantly higher IFN-gamma levels compared to basal release in both groups, whereas no statistically significant differences were found in most experimental conditions as regard PGE2 synthesis. No differences were found in IFN-gamma production by comparing patients with acute viral hepatitis to the control group, whereas PGE2 was significantly increased during the disease. IFN-gamma and PGE2 levels did not show any significant change in acute viral hepatitis during the follow-up. A statistically significant correlation was found only in control group between IFN-gamma and PGE2 levels in unstimulated cultures. PGE2 seems to play a central role in regulating interferon production during viral infection. This may suggest a new therapeutic approach in viral hepatitis utilizing a combination of interferon and prostanoid inhibitory substances, above all in patients who do not respond to interferon therapy alone.