Although the biological effects of some nanomaterials have already been assessed, information on toxicity and possible mechanisms of various particle types are insufficient. Moreover, the role of particle properties in the toxic reaction remains to be fully understood. In this paper, we aimed to explore the interrelationship between particle size, shape, chemical composition and toxicological effects of four typical nanomaterials with comparable properties: carbon black (CB), single wall carbon nanotube, silicon dioxide (SiO(2)) and zinc dioxide (ZnO) nanoparticles. We investigated the cytotoxicity, genotoxicity and oxidative effects of particles on primary mouse embryo fibroblast cells. As observed in the methyl thiazolyl tetrazolium (MTT) and water-soluble tetrazolium (WST) assays, ZnO induced much greater cytotoxicity than non-metal nanoparticles. This was significantly in accordance with intracellular oxidative stress levels measured by glutathione depletion, malondialdehyde production, superoxide dismutase inhibition as well as reactive oxygen species generation. The results indicated that oxidative stress may be a key route in inducing the cytotoxicity of nanoparticles. Compared with ZnO nanoparticles, carbon nanotubes were moderately cytotoxic but induced more DNA damage determined by the comet assay. CB and SiO(2) seemed to be less effective. The comparative analysis demonstrated that particle composition probably played a primary role in the cytotoxic effects of different nanoparticles. However, the potential genotoxicity might be mostly attributed to particle shape.