The reactogenicity and immunological effectiveness of different doses of cholera vaccine for oral administration (in tablets), containing choleragen toxoid, Ogawa and Inaba O-antigens and some of Vibrio cholerae exoenzymes, have been tested on 143 children aged 2-17 years. In this investigation the optimum immunization doses of the preparation have been established: two tablets containing 100,000 binding units (BU) of the toxoid and 2,500 units of O-antigen for children 11-14 years; four tablets containing 200,000 BU of the toxoid and 5,000 units of O-antigen for adolescents aged 15-17 years. An essential advantage of the oral vaccine over vaccines intended for parenteral administration lies in its capacity for inducing the accumulation of secretory antibodies (coproantibodies) in practically all vaccinees.