Phosphatidylinositol 3-kinase (PI3K) signaling cascade is involved in many cell processes that are required for radioresistance, including proliferation, survival, growth, metabolism, and death. At the whole organism level PI3K signaling cascade is involved in lifespan control. In this study the contribution of PI3-signaling cascade to radioresistance of Drosophila melanogaster imago was investigated. It is shown that pretreatment with Pl3-kinase specific inhibitor LY294002 (5, 100 micromol/l) and wortmannin (5 micromol/1) leads to increase of male and female survival after acute irradiation in dose of 30 Gy. The obtained results demonstrate that PI3K specific inhibition induces radioprotective effect on Drosophila melanogaster imago.