Serine/threonine protein kinase ATM (ataxia-telangiectasia mutated) performs a number of aging-related functions in the cell. In addition to regulating the cell response to DNA damage, ATM phosphorylates vacuolar ATPase and thus leads to lysosome degradation and cell senescence. The geroprotective potential of the selective ATM inhibitor KU-60019 was studied in three Drosophila species with different lifespans. KU-60019 was shown to increase the lifespan in the long-lived species D. virilis and moderate-lifespan D. melanogaster. However, the lifespan was reduced after KU-60019 treatment in the short-lived species D. kikkawai. KU-60019 was found to increase the survival in hyperthermia, oxidative stress, and starvation in all of the three Drosophila species, but had no effect on age-dependent changes in locomotor activity. Suppression of the tefu gene for an ATM homolog by RNA interference (RNAi) also increased the lifespan and stress tolerance in D. melanogaster compared with control strains. Thus, the effect of KU-60019 on the lifespan was shown to vary among the Drosophila species. The variation might be related to transcriptome differences observed previously and requires further experimental study.