Background HIV/ HBVcoinfected patients are at high risk of developing chronic HBV infection, liver cir rhosis and hepatocellular carcinoma. In Mozambique, where HIV prevalence is one of the highest in the world, HIV-infected patients are scarcely characterized in terms of HBV coin fection and 3TC-resistance mutations profile. Methods Tocharacterize ART-naïve HIV-infected adults, with and without HBV coinfection, a cross sectional study was conducted between May and November 2012in twohealth centers from Maputo city, Mozambique. Subjects were consecutively enrolled in the study and, then, tested for hepatitis B surface antigen (HBsAg). Moreover, CD4 + Tcells count, HBV DNAinplasma, HBVgenotyping and3TC-resistance mutations profile of HBV were assessed in HIV/HBV coinfected patients. Results In total, 518 patients were enrolled in the study. The median age was 33 years old and 66.8% werewomen. ThemedianCD4 + T cells count was 361 cells/mm 3 and47(9.1%) were coinfected with HBV. Out of 46 coinfected patients, 24 (55.2%) had HBV DNA 20-< 20 000and12(26.1%)hadHBV-DNA 20000.APRI>2.0wasreportedin4.3%ofcoin fected and 1.7% of monoinfected patients (p = 0.228), while FIB-4 > 3.25 was reported in 4.4%ofcoinfected and 1.3% of monoinfected patients (p = 0.112). Genotype A was the most frequent, identified in 25/27 (92.6%) patients, whereas genotype E was present in 2/27 (7.4%) patients. No patient had 3TC-resistance mutations.