Worldwide, 880,000 people die each year as a result of infection with the hepatitis B virus (HBV). Antiviral drugs that can suppress replication of the virus are available. However, these must be taken for decades, as there is yet no curative therapy for chronic HBV infection available. Biomarkers—biological molecules in blood serum that can be used to monitor the course of chronic infection and the response of patients to new therapies—are needed to guide the development of these therapies and to assess their efficacy. Potential biomarkers have now been evaluated in a widely acclaimed review and a roadmap for their further development has been established.