Abstract: To investigated the distribution of HCV genotypes and the susceptibility of HCV infection in northeast China, 579 patients in fected with HCV were divided into p ersistently normal ALT group and elevated ALT group on the basis of serum ALT le vel.HCV genotypes and HBV markers of them were detected by sandwich hybridizatio n on microplate and ELISA assay.Gene chips were used to analyze the frequency of HLA-DRB1 in 30 patients with HCV infection and 30 healthy controls.The results showed:Infection rate of HCV Ⅳ/2b was 51.12%, the highest in the four genotype s.Normal level of serum ALT was found in 34.72% patients with HCV infection.Inf ection rates of HCV Ⅱ/b and mixed type HCV infection in elevated ALT group were higher than those in normal ALT group (P<0.05) .Positive rates of type I/1 a and Ⅲ/2a were higher and that of mixed type were lower in patients who coinfe cted with HBV, significant difference was found between those coinfected and infe cted HCV alone (P<0.05) .Mixed type HCV infection were mostly found in thos e patients with more than twice transfusion history.The frequency of HLA-DRB1*04 and HLA-DRB1*13 in patients with HCV infection were higher than those in contro l (P<0.05) .In conclusion, HCV Ⅳ/2b was the major genotype in northeast Chi na.About 34.72% HCV infection presented normal ALT, which might be the hidden so urce of HCV infection.HCV Ⅱ/1b and mixed type HCV infection were liable to indu ce liver damage.Type Ⅰ/1a and Ⅲ/2a but not two or more types coexist did compl icated with HBV easily.Accept transfusion or blood manufactures repeatedly may b e the major reason of two or more types of HCV coexist.Those people with HLA-DRB 1*04 and HLA-DRB1*13 allels may be more liable to suffer HCV infection.