Hepatitis C virus (HCV) is a member of the hepacivirus genus in the family of Flaviviridea, classified into six genotypes, most of which comprise multiples sub-genotype, among them, the genotype 1 and 6 are distributed widely. The HCV subtypes may spread among the geographical area lead to different HCV genotypes distribution in each region. Objective: to identify the original transmission of HCV in HaiPhong. Methods: (1) Crosssectional survey of HCV genotype distribution among 633 injecting-drug users (IDUs) and femal sex workers (FSWs) at some centers in HaiPhong. (2) Serological an ti-HC V detection using HCV PHA Kit (Abbort Japan, Tokyo, Japan)
(3) Genotyping HCV by direct sequencing using neseted PCR product or clonal sequencing
(4) Construct the phylogenetic tree by the neighbor-joining method and Njpplot, Clustal W programme. Results: Among 633 paticipants, 376 (59,4 percent) were anti-HCV positive, including 66,87 percent (329/492) cases ofIDUs and 33,33 percent (47/141) cases of FSWs. From nested PCR positive cases, 137/256 samples of IDUs and 26/31 samples of FSWs were succesfully sequencing base on 5 'UTR-core and NS5B region, 34/137 (23,13 percent) IDUs and 3/26 FSWs were coinfected sub-genotype HCV. Genotype 6a/1a were most common genotypes. Conclusion: Serological anti-HCV among IDUs in Hili Phong was 66,87 percent (329/492) and among FSWs was la 33,33 percent (47/141). Coinfected sub-genotype HCV among IDUs was 23,13 percent and among FSWs was: 11,54 percent. Genotype 6a/1 a were most commoh genotypes, genotype 1 a HCV in Hai Phong was associated with which in Hanoi. The genotype 6a in Hai Phong was significaltly associatf!d with genotyope 6a strains in Yunnan, Southern China.