BackgroundHepatitis B virus (HBV) and human immunodeficiency virus (HIV) co-infection in South Africa is estimated to be between 5% and 23%; however, only limited evidence is available. Co-infection increases the risk of chronification of HBV, liver cirrhosis and death.ObjectiveTo assess the HBV and/or HIV co-infection rate amongst the adult antiretroviral treatment cohort at the TC Newman ART Clinic in Paarl, Western Cape.MethodsIn a retrospective, cross-sectional study, the routine hepatitis B surface antigen screening results for all adult HIV patients who were started on antiretroviral treatment over a period of 19 months were collected and analysed for gender, CD4 count and age.ResultsAmongst the 498 participants (60% female participants), the Hepatitis B surface Antigen positivity rate was 7.6%. Male gender, age between 50 and 59 years and a low CD4 count were correlated with higher rates.ConclusionUseful insight could be obtained by analysing routine data. The prevalence of almost 8% confirms the need for testing of HIV-positive patients for hepatitis B.