Hepatitis C virus (HCV) is a major cause of post transfusion non-A, non-B hepatitis. The virus contains a positive-strand RNA genome comprised of approximately 9,400 nucleotides. HCV E2/NS1 is probably an envelope glycoprotein (E2). The E2 hypervariable domain appears to contain isolate-specific antibody-binding linear epitopes. Recently, comparative sequence analysis of all the complete and partial HCV sequences published to date indicates that known genotypes of HCV can be classified into six basic groups. We report here that the prevalence of HCV-I, HCV-II, and a mixed form are 77.2%, 11.4%, and 11.4%, respectively. Patients with anti-HCV and HCV-RNA positive chronic active hepatitis received 6MU of interferon-alpha or beta everyday for two weeks followed by 6MU thrice a week for 14 weeks. Complete response to interferon treatment was defined as an ALT level normalized within six months after the end of treatment and maintained within the normal limit for an additional six months. Complete response was found in 42.9% of patients treated for 16 weeks. In a six month follow-up of the complete responders, clearance of viremia was observed in 90.3% at the end of interferon treatment and in 71.0% six months after the end of interferon treatment.