Background: Hepatitis B virus (HBV) infections remain a global health issue with complications including liver cirrhosis and hepatocellular carcinoma. Individuals co-infected with Human Immunodeficiency Virus (HIV) and HBV have increased liver-related morbidity and mortality compared to those with HBV mono-infection. Vaccination is a potent intervention to prevent HBV infection, but certain critical populations including people living with HIV are less likely to achieve seroprotection after vaccination. Seroprotection (antibody to hepatitis B surface antigen [HBsAb] titer ≥10 IU/mL) was historically poor, with trial rates ranging from 34 to 88% and improving with immunologic reconstitution and viral suppression. We hypothesized that the seroprotection rates (SPR) in a clinic population of Veterans would reflect the improving immunologic status of the cohort.