Sixty patients of both sexes with biopsy-proven chronic hepatitis C were randomized to receive lymphoblastoid interferon 3 MU or 6 MU three times weekly for 6 months. A follow-up period of 3 months at the end of the therapy was scheduled. Thirty-two patients (53.3%) normalized alanine aminotransferase at the end of the therapy. Of these, 17 received 3 MU (56.7%) and 15 (50%) received 6 MU. Eighteen of the 32 patients (56.2%) relapsed in the follow-up period after treatment. No significant difference in relapse rate was observed between the two groups. The overall percentage of the non-responder patients was 36.6%. The treatment was discontinued because of non-compliance and/or side effects in six patients (10%): three in the 3-MU group and three in the 6-MU group. An improvement in liver histology was observed in about a quarter of chronic active hepatitis patients whose overall diagnosis changed to chronic persistent hepatitis. Knodell's score system showed a significant improvement (p < 0.05) with regard to peripheral necrosis, fibrosis and total score. HCV-RNA was positive at the beginning in all patients and it became undetectable in almost all responder patients. In some cases there was no correlation between viraemia and biochemical signs of liver disease. Our study shows that 6 MU does not increase the response rate compared to 3 MU. Moreover, the lower dose is able to improve the liver histology and to abolish the HCV viraemia in responder patients.