Background: Hepatitis B virus (HBV) and HIV are endemic in Uganda. Co-infection is common and leads to rapid progression of liver disease. Burden of co-infection is unknown yet most patients are on lamivudine-only ART where resistance is frequent. Most patients are initiated on antiretroviral therapy (ART) without knowing their HBV status. Objectives: To determine burden of co-infection and HBV viral suppression among patients on ART in NorthernUganda. Methods: We recruited HIV infected adult patients on ART in a cross-sectional study. Age, sex, ART regimen and duration were recorded. Hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBcAb) and liver panel were performed. For those HBsAg+, hepatitis B e antigen (HBeAg) and HBV DNA were performed. CD4 cell count was recorded. Results: Three hundred patients were recruited. Twenty (6.7%) were co-infected, while 41% were anti-HBcAb+. Overall 188 (62.7%) were on lamivudine- only HBV active drug. Median ART duration 2 years (IQR 1-5), mean CD4+ cell count 317 cells/microlitre (SD 255-557). Of 20 HIV/HBV co-infected, 11/20 (55%) were on lamivudine-only ART, median duration 1.5 years. Nineteen (95%) had undetectable HBV DNA. Seventeen (85%) were HBeAg negative. Mean CD4+ cell count 327 cells/microlitre (SD 197-482). Conclusion: A large proportion of patients were on lamivudine- only HBV-active ART. Resistance may occur long term thus testing for HBV and correct ART is recommended.