This study assessed the prevalence of and correlated factors for chronic hepatitis B infection (HBV) among HIV patients attending the Reference Center for Sexually Transmitted Infections (STI) and AIDS in Vitória, ES, Brazil. HIV patients were studied from 1993 to 2004, using information recorded in a database of the STI Clinic. Demographic data, clinical characteristics, patterns of risk behavior and test results (ELISA-HIV, IFA-HIV, HBsAg, viral load and CD4 counts) were analyzed. We analyzed 851 HIV patients. Median age was 35.0 (interquartile range 30; 42) years and median years of education was 8.0 (IQR 5; 11). The prevalence of chronic HBV was 3.8% (95% CI 2.5-5.1). Illicit drug use was reported in 185 (21.7%) cases, alcohol abuse in 80 (9.4%) cases, men who have sex with men in 116 (13.6%) cases, and past STI in 320 (37.6%) cases. Chronic HBV was associated with intravenous drug use, male gender, STI associated with HIV diagnosis, and death. There is a need for prevention and assistance strategies to control the evolution of this infection in HIV patients.