The experimental study of the DNA interaction with three cadmium coordination compounds [Cd(phen)₃](CH₃CO₂)₂, [Cd(phen)₂(H₂O)₂](CH₃CO₂)₂, and [Cd₂(phen)₄(H₂O)₂](CH₃CO₂)₄ was carried out using spectrophotometry, viscosity, and dynamic light scattering methods. The role of the solution ionic strength (concentration of NaCl) was analyzed. All compounds can penetrate (fully or partly) to the major or minor DNA grooves. It was shown that, in addition to the important role of electrostatic interactions in the formation of the complex, intercalation of the 1,10-phenanthroline ligand occurs for compounds [Cd(phen)₂(H₂O)₂](CH₃CO₂)₂ and [Cd₂(phen)₄(H₂O)₂](CH₃CO₂)₄. Compound [Cd(phen)₃](CH₃CO₂)₂ binds to DNA externally. The coordination bond between cadmium and DNA was formed in DNA complexes with [Cd₂(phen)₄(H₂O)₂](CH₃CO₂)₄. Preliminary computer modeling of the DNA interaction with the compounds used was performed.