Liver histology was compared in patients with chronic hepatitis C to note the differences between responders and non-responders to interferon treatment. Fifty-eight patients were administered interferon in varying doses and over various periods, and were then followed up for 1 year. According to the improvement status of serum alanine aminotransferase (ALT) levels during this period, the patients were classified into complete responders who showed complete normalization of ALT; partial responders who exhibited a significant decrease, but not complete normalization of ALT; and non-responders who did not reveal any significant decrease of ALT. Before application of the interferon treatment, liver biopsies were analyzed in four parameters and given scores from 0 to 5 for three groups in cord with no prior knowledge of the efficacy. The parameters included necroinflammation, fibrosis/lobular distortion, portal lymphocytic reaction and portal (or fibrous septal) outline destruction. Results indicated that there were no significant differences in the score of necroinflammation and portal lymphocytic reaction between the complete responder group and the non-responder group. In contrast, the complete responder group exhibited weaker fibrosis/lobular distortion and less portal outline destruction than the non-responder group. The partial responder group was more akin to the former group in these parameters. Thus, it is safe to conclude that liver histology may predict the efficacy of interferon treatment.