Hepatitis B virus core antibody is the antibody corresponding to the core antigen in hepatitis B virus, abbreviated as HBcAb, and includes three types: IgM, IgA and IgG. Hepatitis B virus core antibody is an early marker of hepatitis B infection and is a hallmark antibody. Hepatitis B virus core antibody is one of the hepatitis B two-to-one tests, which does not have much significance when analyzed alone and needs to be combined with other tests in the hepatitis B two-to-one test. IgM is an important indicator of acute hepatitis B. It is generally the earliest antibody that appears after the body has been infected with the hepatitis B virus and can last up to six months; IgG is the latest antibody that appears and can last for years or even decades, indicating that the body has recovered from previous hepatitis B virus infection. In the hepatitis B hemoglobin, positive simple hepatitis B core antibody can be seen in the following cases: early recovery from acute hepatitis B infection, people who have been infected with hepatitis B virus in the past and some hepatitis B virus carriers, if the simple hepatitis B core antibody is positive, further serological tests are needed to determine whether the person is a hepatitis B patient and whether the virus is infectious and whether the virus is in an active replication phase. The hepatitis B virus core antibody is clinically significant in determining whether hepatitis B virus infection is present.