This paper reports the synthesis and characterization of ZnO nanoparticles prepared by soft chemical process. The nanoparticles of ZnO possess wurtzite hexagonal phase and were used for the induction of cell death in malignant human T98G gliomas, KB epithermoids and HEK normal non-malignant kidney cells. By applying ZnO nanoparticles, the cells exhibit that the nanoparticles are more efficacious on T98G cancer cells, moderately effective on KB cells and least toxic on normal human HEK cells. The results demonstrated that the treatment with ZnO nanoparticles sensitize T98G cells by increasing both the mitotic (linked to cytogenetic damage) and interphase (apoptosis) death. The ZnO nanoparticles behave as genotoxic drugs, since they induce a micronucleus formation in cells. The present study could be helpful in designing more potent anticancer agents for the therapeutic uses.