The results of demographic analysis of survival of different Drosophila lines have shown that recessive lethal mutation located in X-chromosome locus 6D1-7A2, as compared with wild type strain, in heterozygote leads to aging speed deceleration (decreasing of mortality trajectory slope), median (20%) and maximal (15-20%) life span increasing. Further investigations (complementation analysis with duplicated loci) will enable to discover, whether it is unknown life span gene.