Conformational properties of DNA molecule upon its complexation with binuclear compounds of bivalent platinum in the cis configuration containing pyrazine ligand were studied by circular dichroism, viscometry, and dynamic birefringence. Comparison with an active antitumor agent cis-diamminedichloroplatinum (cis-DDP) was made. Experimental data indicate that interaction of these compounds with DNA results in the formation of a coordination bond of platinum with nucleic bases. The structure of the complex depends on the ratio of platinum and DNA concentrations in the initial solution. The study of DNA protonation in complex with the binuclear coordination compound showed that the binding of platinum with DNA bases involves the N7 atom of guanine. Competition was observed between the studied compound and cis-DDP for the binding site on DNA. The macromolecule binds stronger with the binuclear platinum compound than with cis-DDP.