A method of determining antibodies by their adsorption on large-pore or surface immunosorbents with subsequent treatment of the carrier with anti-immunoglobulin serum and antiphage serum isologous to the antibodies and then with the bacteriophage has been presented. The adsorbed virions are split off by means of papain-induced hydrolysis of the antibody complex. The antigens are determined by the reaction of phage fixing inhibition. The method permits to determine small amounts of antibodies to proteins, haptenes and cells with objective calculation of results.