Abstract: Objective To understand the genotypic distribution of HCV among HIV-1/HCV co-infected injection drug users (IDUs)．b>Methods Plasma samples of HIV-1 seropositive IDUs identified from 2007 to 2012 were collected for the HCV sero-test. RNA genome of HCV-positive samples was purified, and then the HCV Core and NS5B fragments were amplified by RT-nested PCR and sequenced. The target gene sequences were used for HCV genotyping/subtyping via phylogenetic analyses．Results A total of 209 samples of IDUs aged between 18 and 49 years were collected from cities of Huizhou, Dongguan, Yangjiang, Yunfu, Qingyuan, Foshan, Zhongshan, and Jiangmen and 196 cases were males (93.78%). The samples of the IDUs were mainly from Yangjiang and Dongguan (36.84%). Among the 209 samples tested, 166 (79.4%) were found to be positive for HCV antibody. Phylogenetic trees showed that HCV sequences were clustered with standard strains la (10.6%), lb (9.9%), 2a (1.4%), 3a (22.7%), 3b (11.3%), and 6a (44.0%), respectively.Conclusion The most predominant subtype was HCV 6a in IDUs infected with HIV-1 in Guangdong Province, followed by the 3a subtype.