Hepatic fibrogenesis is a dynamic process which characterizes the course of chronic hepatitis. It has stimulated interest in the possible effect of interferon therapy on liver fibrosis. We have evaluated a panel of serum markers of fibrogenesis, namely N-terminal procollagen III peptide (PII-INP), C-terminal procollagen I peptide (PICP), laminin and hyaluronate in 35 patients with chronic hepatitis type C, before, during and after interferon treatment. Before treatment, PIIINP was elevated in 8.5%, 44% and 71% of patients with chronic persistent hepatitis, chronic active hepatitis and cirrhosis, respectively, while the corresponding figures for PICP were 0%, 50% and 46%, and for laminin 16.5%, 70% and 71%; hyaluronate was elevated in only five out of seven patients with cirrhosis. Patients with high PIIINP levels at presentation and a persistent response to treatment showed persistent normalization of this parameter, which was not observed in non-responders. In contrast, the other markers showed no significant correlation with interferon response. These results indicate that PIIINP correlates with interferon response in chronic hepatitis type C.