Background and Objectives: Hepatitis C virus and Human Immunodeficiency Virus (HIV) share the same rate of transmis- sion. HIV/HCV co-infected individuals may result in faster progression of liver fibrosis and highly increase the risk of cir- rhosis, hepatocellular carcinoma development. Thus this study was conducted to determine co-infection of HCV genotypes in positive HIV patients in Ahvaz city, Iran. Materials and Methods: The sera samples were collected from confirmed 78 infected HIV, 67 (85.89%) males and 11 (14.1%) females. All sera samples were tested for HCV Ab using ELISA test. The HCV Ab positive samples were tested for detection of 5' untranslated (UTR) and core regions of HCV genome using nested RT-PCR. The PCR products of 5UTR and core regions were sequenced to determine HCV genotypes. Results: Among the 78 infected HIV, 25 (32.05%) cases including 20 (25.64%) males and 5 (6.41%) females were positive for HCV Ab (p=0.316). 53 (67.94%) of HIV patients were negative for HCV Ab. Among 25 positive HCV Ab, 19 (24.35%) cases including 15 (19.23%) males and 4 (5.12%) females were positive for HCV RNA (p=0.447). The PCR products of 5 positive samples were randomly sequenced. The results of sequences and alignments showed that the detected HCV geno- types were three 3a and two 1a. The occurrence of genotype HCV 1a was found in one male injecting drug user Injecting Drug User (IDU) and one female. The HCV 3a genotype was detected in the three males IDU. Conclusion: The results of this survey indicated that 32.05% of HIV patients were positive for HCV Ab, among them 24.35% were positive HCV RNA. HCV genotype 3a was dominant and detected in the three males IDU.  Regarding the consequences of HIV/HCV co-infection, it is suggested that HCV RNA detection should be regularly checked in individuals infected with HIV.