Introduction: Hepatitis B is a transmissible disease, it is estimated that globally more than two billion people in the world have been infected with hepatitis B virus, of which 350 million are chronic carriers of hepatitis B surface antigen, and this chronic infection causes cirrhosis and liver cancer. In Peru, hyperendemic zones have been detected in the country's jungle. Cajamarca is the third department with the highest rates of liver and bile duct cancer. Celendín is a district located in Cajamarca, which borders the jungle, and maintains a high contact with it for trade and tourism. There have been no previous studies of this virus in Cajamarca´s population. Objective: to determine if there is a high seroprevalence of the hepatitis B virus in the adult population of the Celendín-Cajamarca district, in 2018. Material and methods: a cross-sectional study was carried out in 4...