In this study, the prevalence, genotype frequency, and risk factors for HBV infection in 768 HIV-infected subjects living in Piauí were determined. Forty-six (6.0 %) HIV-positive subjects were reactive for HBsAg and positive for HBV-DNA. Genotypes A (71.8 %), F (23.9 %) and D (4.3 %) were identified. Multivariate analysis revealed an association between HIV-HBV coinfection and male gender, older age groups, unprotected sex, reporting more than ten sexual partners throughout life, STD, and tattooing. This study shows the importance of monitoring sites and professionals who perform tattooing and practice safe sex to prevent the spread of HIV and HBV infections.