In this study, the effects of water extract obtained from Usnea longissima Ach. (Ule), a lichen species, on the longevity of Drosophila melanogaster was investigated. The effects of different concentrations of Ule (0.5, 1.0, 1.5, 2.0 and 2.5 ml/100 ml medium) were separately administered as one-by-one in female and male populations of D. melanogaster for control and application groups. In the first three application groups (0.5-1.5 ml/100 ml medium) of each population, the longevity increased, whereas those of the last two groups (2.0-2.5 ml/100 ml medium)) were shorter than that of the control group. It was found that the difference between the groups was significantly important (p<0.05).