Prophylaxis of toxoplasmosis consists of a complex of general medical and veterinary measures. Of importance is detection of latent forms of toxoplasmosis in pregnant women and their timely treatment. Thorough clinical and immunological examination of persons with prolonged diseases of obscure etiology is necessary. Suggestions are given for dispensary observation of persons who sustained the disease and had positive immunological reactions for toxoplasmosis. Materials on prophylaxis of hemotransfusion transmission of the infection are presented for the first time. A number of recommendations concerns measures of general organization and also planned prophylactic examination with the use of immunological methods of some groups of population with increased risk of infection.