Background :There are several serological subtypes (serotypes) of hepatitis C virus (HCV) which can be detected by a serological enzyme immunoassay (EIA) method which detects the HCV subtype-specific antibodies against the NS4 legion of the virus. We determined the HCV serotypes chronic HCV infected patients in terms of clinical applications. Method :Subtypes based on Simmonds` classification were detected in chronic HCV patients serologically and viral loads quantitated with branched DNA (bDNA) assay. The EIA was compared with multiplex PCR method. Result :The serotype 1 (Simmonds` classification, 1a, 1b, 1c), the most prevalent form in Korea followed by serotype 2 (Simmonds` classification,2a,2b,2c). The distribution of serotypes and HCV viral loads were not different according to disease severity The patients infected with serotype 1 had higher viremic level (serotype 1, 7.4 ±155 MEq/mL; serotype 2, 1.1±2.2 MEB/mL, P=0.017). The serotype matched with the genotype in 85.7% (18/21) of cases. Conclusion :HCV serotype 1 is the most prevalent form in Korea and seemed to be able to more actively replicate than serotype 2. Both multiplex PCR and EIA can be used for detecting HCV subtypes and mutually interpretable.