IL-6 production by peripheral blood mononuclear cells (PBMC) was studied in patients with chronic hepatitis B virus (HBV) infection and primary biliary cirrhosis (PBC) using the ELISA method. Spontaneous production of IL-6 was significantly increased in patients with HBeAg+ chronic hepatitis (CH). The cultures stimulated with lipopolysaccharide and lectin-free interleukin-2 (IL-2) showed enhanced IL-6 production both in controls and all patient groups compared with culture without any stimulation. IL-6 production in response to IL-2 was higher in patients with HBeAg+ CH and PBC than in controls. In PBMC with increased IL-6 production, monocyte function was increased in patients with HBeAg+ CH and PBC, while B cells from PBC showed elevated response to Staphylococcus aureus Cowan 1. IL-6 production in the presence of HBeAg was greater in anti-HBe+ patients than in HBeAg+ ones. These results suggest that IL-6 response is involved in the immune response in patients with chronic liver disease.