Starburst^TM PAMAM dendrimers are novel polymers with a molecular architecture characterized by regular, dentritic branching with radial symmetry. Having high density of positive charges on their surfaces in physiological condition because of the protonization of amino groups on the surfaces, and complexing with genetic materials on the basis of electrostatic interactions, those Starburst^TM PAMAM dendrimers deliver genes into alive cells.In order to characterize the potential effects of Starburst^TM PAMAM dendrimers as a carrier for DNA transfection, six different types generations of Starburst^TM PAMAM dendrimers were investigated for their capabilities in binding DNA, and the effects on both DNA transfection and maintenance of cell viability was evaluated in vitro. The experiments demonstrated that it was the full generations but not the half generations of Starburst^TM PAMAM dendrimer could transfect eukaryotic cells efficiently. The dendrimer/DNA complexes were very steady, no dissociation of the complexes was detectable in a large scope of pH(2～10). The complexation of Starburst^TM PAMAM dendrimer and DNA prevent the reaction that endonuclease dissociates the DNA. In a certain range of dendrimers to DNA charge ratios, the Starburst^TM PAMAM dendrimer with higher generations showed much better transfection efficiency than those with lower generations. The transfection efficiency was also variable in different cell lines. Starburst^TM PAMAM dendrimers complexing with DNA have no or very low cytotoxicity at the concentrations effective for DNA transfection (≤1.3×10^-1 g/L). However, the cytotoxicity of Starburst^TM PAMAM dendrimers without binding DNA could be detected at a lower concentration. The results demonstrated that Starburst^TM PAMAM dendrimers,as a novel type of low toxicity, non-viral DNA delivery vehicle,had promising potential to mediate DNA transfection in vitro. It provide primary experimental basis for the application of the nanometer material-Starburst^TM PAMAM dendrimers in vivo as DNA delivery carrier.