In order to characterize intrahepatic cytokine production, the mRNA levels of interleukin (IL)-2, -4, and -10 and interferon (IFN)-gamma were semiquantitatively determined by reverse-transcription competitive polymerase chain reaction in liver specimens from patients with chronic hepatitis C (n = 23), chronic hepatitis B (n = 9), or primary biliary cirrhosis (n = 12) and normal liver (control) specimens (n = 12). IL-4 mRNA was undetectable. Similar IL-10 mRNA levels were detected in all samples studied, including the controls. Mean IFN-gamma and IL-2 mRNA levels were elevated in chronic inflammatory liver disease. IL-2 mRNA levels were similar in all 3 patient groups, but intrahepatic IFN-gamma mRNA levels were significantly higher in chronic hepatitis C than in chronic hepatitis B or primary biliary cirrhosis patients. This predominance of IFN-gamma may indicate a lower susceptibility of hepatitis C virus to the antiviral effects of this cytokine. The presence of IL-10 in normal liver may impair the induction of antiviral immune responses.