The comparative analysis of the titers of antibodies to the preparations of S. aureus teichoic acids and DNA in the sera of healthy donors and patients with infectious endocarditis and rheumatic carditis was made by means of ELISA. The sera of patients with infectious endocarditis and rheumatic carditis, in contrast to the sera of healthy donors, showed the presence of antibodies to DNA in 23.5-76.2% of cases. The correlation between the presence of antibodies to S. aureus teichoic acids and DNA in the sera of the patients was weakly pronounced.