To study the genotypes of HCV infection in Shanxi Province and the response of HCV genotypes to interferon therapy, the genotypes of HCV were analysed by restriction fragment length polymorphism in 94 chronic hepatitis C patients who were positive for HCV RNA (RT-PCR). It was shown that 80 patients (85.1%) were group I infection, 12 (12.8%) were group II infection and 2 (2.1%) were group I/II co-infection. 45 chronic hepatitis C patients with different genotypes (35 with HCV group I, 10 with group II) received rIFN alpha-1b 3 MU three times a week for 6 months and were followed up to 12-34 months. The responsive rate was significantly higher in patients with group II infection (80%) than that in patients infected with group I (37.1%) (P < 0.05). Sustained response was observed in 60% for group II and in 17.1% for group I (P < 0.025). The date indicated that HCV group I is the major type of HCV infection in Shanxi Province the and HCV genotype seems to be an important factor in determining the response rate to IFN treatment in patients with chronic hepatitis C.