Chronic hepatitis B describes a spectrum of disease resulting from chronic hepatitis B virus (HBV) infection. About a third of the world's population has serological evidence of past or present HBV infection, and 350-400 million people have chronic HBV infection.1 In the UK about 326 000 people are thought to have chronic hepatitis B.2 In some people, chronic hepatitis B may cause liver fibrosis, cirrhosis, and hepatocellular carcinoma; in others it is inactive and does not lead to important health problems.3 Antiviral therapy suppresses HBV replication and decreases the risk of progressive liver disease.4 This article summarises the most recent recommendations from the National Institute for Health and Care Excellence (NICE) on the diagnosis and management of chronic hepatitis B in children, young people, and adults.5 NICE recommendations are based on systematic reviews of the best available evidence and explicit consideration of cost effectiveness. When minimal evidence is available, recommendations are based on the Guideline Development Group's experience and opinion of what constitutes good practice. Evidence levels for the recommendations are given in italic in square brackets. ### Assessment and referral in primary care #### Children, young people, and adults who are seropositive for HBV surface antigen (HBsAg)