This invention reveals the pharmaceutical composition that includes the surface antigen (HBsAg) of the hepatitis B virus (HBV) and the antigen of the nucleocapsid (or core, HBcAg) of the same virus. The HBcAg of this composition contains messenger ribonucleic acid (mRNA) at a proportion of over 45% of the total amount of ribonucleic acid (RNA) in this antigen. Because of the changes in the constitution of the antigens forming it, the composition of the invention is useful for the prevention or treatment of chronic hepatitis B. It also covers the use of this pharmaceutical composition in the production of a drug for immuno-prophylaxis or immunotherapy against HBV infection, and its use to increase the immune response against an additional antigen that is co-administered with the mixture of these antigens.