Co-infection with Hepatitis B (HBV) virus and HIV is common due to similarity of their transmission methods. However, the prevalence of concurrent infection in different societies, shows the crucial role of various risk factors in different populations. Therefore, the present study was performed to examine risk factors of transmission of HBV in patients with HIV in a care center for AIDS patients in Rasht City. This case-control study was carried out on 60 HIV positive patients, who visited the Infectious Diseases Center of Razi Hospital of Rasht from November, 2015 to March, 2016. Participants were assigned to two 30-member experiment and control groups. They were adjusted in terms of age group (18-30, 30-40, 40-50, and 50-60), gender (male and female), and marital status (married, single, divorced, and widowed) and visited by an infectious diseases specialist according to routine examinations. Data was recorded in a questionnaire for each subject. The mean age for the experimental group was 35±6.1, and for control group was 36.6± 5.7 years. Both univariate and multivariate analyses of development of HBV infection and variables including Illegitimate sexual intercourse, use of intravenous injection drugs, positive history of imprisonment, and tattooing (p value < 0.05) showed existence of significant relationships. Injection of illegal intravenous drugs, history of imprisonment, illegitimate sexual intercourse, and tattooing are four important risk factors for transmission of HBV infection to HIV patients. In addition, the master risk reduction program may include provision of clean disposable tools for intravenous injection of drugs and tattooing.