To challenge the hypothesis that interferon (IF) production in chronic hepatitis-B virus liver disease is defective, lymphocytes from 14 patients with chronic active liver disease (CALD); from nine patients with chronic inactive liver disease (CILD), and from six healthy chronic carriers (HCC) were stimulated by Newcastle Disease virus. The patients with CILD showed a weak IF response by comparison with the controls (P less than 0.0005), whereas IF production by CALD patients and the HCC did not statistically differ from IF production in the healthy hepatitis-B surface antigen negative subjects who served as controls. These results indicate that IF treatment of CALD does not rely on a completely proved background.