Water-soluble cationic polypyridylphenylene dendrimers (wPPPDs) of different generations and various contents of pyridyl and phenylene moieties were synthesized. Interaction of wPPPDs with DNA resulted in the formation of polyelectrolyte complexes stable at physiological pH and ionic strength. Noticeable contribution of hydrophobic interactions provided by phenylene groups of the dendrimer in the complex stability was ascertained. Data obtained by turbidimetry and a sedimentation assay, as well as potential measurements, strongly implied the inaccessibility of positively charged pyridinium groups situated in the inner part of the dendrimer molecules for interaction with the rigid double helix. Positively and negatively charged water-soluble nonstoichiometric polyelectrolyte complexes were prepared and phase separations in their water-salt solutions were investigated, According to DLS measurements Supported by the sedimentation assay, the addition of wPPPD in DNA Solution in a wide range of the Mixture composition (before phase separation) led to two coexisting Populations of nanoparticles related to the soluble DNA/wPPPDs complex and practically unbound DNA. The revealed spontaneous formation of nanoparticles of the positively charged Soluble DNA/wPPPDs complexes stable at ionic strength close to the physiological one is extremely encouraging for the development of the wPPPD vehicle to deliver gene materials to the cell.