BackgroundThe National Health Service (NHS) in England commissioned opt-out testing in London Emergency Departments (ED) in April 2022 to allow early identification and management of hepatitis B (HBV) and hepatitis C virus (HCV) infection in patients unaware of their infection status. MethodsAll adults over the age of 16 undergoing blood tests in the ED at the Royal Free Hospital were tested for HBV surface antigen and anti-HCV IgG unless they opted out. Data was collected between the 12th of April and 22nd of August 2022. OutcomeOf 11,215 patients tested for HCV, 164 patients were found to be anti-HCV IgG positive, giving a seroprevalence rate of 1.46 %. 52 of the anti-HCV IgG positive patients did not have any previous HCV serology result. 23 of the anti-HCV IgG positive patients were also HCV RNA positive giving an RNA seroprevalence of 0.21 %, and 17 of those were new diagnoses of HCV viraemia. For HBV testing, 82 (0.73 %) out of 11,192 patients tested were found to be HBsAg positive, including one patient who presented acutely with a positive HBV core IgM. 39 of the HBsAg positive patients were previously unknown to us; of these, 9 had an HBV viral load of more than 2000 IU/mL, including 3 patients with positive HBV e antigen and one patient with hepatitis D virus co-infection. ConclusionOpt-out screening of HBV and HCV in ED is effective at identifying patients with previously undiagnosed viral hepatitis infection and providing an opportunity to engage them in specialist care.