In the paper was presents the results of a study on several grounds that characterize the genotoxic effect (fertility, vitality, mortality at early stage, late embryogenesis, larvae and pupae), in seven lines of wild type D. melanogaster that were exposed to treatment of cytotoxic drugs aminopterin (AP) and methotrexate (MT). The effects of cytotoxic drugs on the average individual fecundity and viability of Drosophila at different stages of development were traced. Interline differences according to the grounds were studied. The effect on selection background of chemical stress, as an adaptive mechanism were marked.