We investigated serum concentrations of acute-phase-proteins (alpha 1-antitrypsin (alpha 1-AT), alpha 1-acid glycoprotein (alpha 1-sGP) and C-reactive protein (CRP)), and of complement components C3 and C4 during the course of acute hepatitis A and hepatitis B and correlated it to age and sex of the patients. Whereas a small increase of all three acute-phase-proteins was seen during acute hepatitis A, alpha 1-AT and CRP, but not alpha 1-aGP were found to be elevated during hepatitis B. A moderate elevation of C3 and C4 serum levels, more pronounced in hepatitis B than in hepatitis A, was seen followed by a slow return to normal. A systemic acute phase response seems not to be present during acute viral hepatitis in spite of the pronounced local inflammatory changes in liver tissue.