The long-term consequences of the X-irradiation of Drosophila melanogaster fruit fly one-hour eggs with doses of 0.25, 0.50, 0.75, 1, 2 and 4 Gy were investigated. Longevity hormesis was observed in males exposed to 0.5 Gy and 0.75 Gy, but no longevity increase was observed in females. The electrophoretic analysis has shown that the amount of the DNA segments resulting from cleavage in S1 nuclease-sensitive sites (<3 kb) reached 39.2% of the total DNA from control males. DNA from the irradiated males had a smaller amount of such fragments (10-30% in different experimental groups). These findings indicate that the longevity hormesis may be associated with irradiation-induced long-term structural and/or functional DNA modifications.