Individuals carrying occult (latent) hepatitis B pose epidemiological threat. Testing donated blood donors for surface antigen HBsAg (hepatitis B virus, HBV) only does not allow to assume the blood safe from the point of view of infections, which can result in post-transfusion transmission of infection. Lack of confidence here is due to the fact that the virus is present in the body even when HBsAg is negative. The study analyzes data of 61,155 blood donors of the Republican Blood Center (Kazan), collected in 2010–2014. The tests applied were those aimed at detecting HBsAg, anti-HBc-total, anti-HBc IgM (enzyme immunoassay), and determining DNA of the virus in the blood by polymerase chain reaction in "real time". It was found that donors with occult hepatitis B are identified each year, but their numbers decrease gradually. To prevent the spread of the virus it is recommended to add the anti-HBc-total test to the standard set of diagnostic tests.