Abstract: Observations on two tests in exploring genetic effect of the factors of T_7A—S1 rocket flight with drosophila melanogaster show that the percentage of the eggs without X-chromo-some is increased and the percentage of the eggs with double X-chromosomes is not changed in the total number of eggs laid by female parents in the days after flight (mainly the fourth to sixth). The character is not that one or two individual laid a larger number of eggs without X-chromosome, but that there is an increase in the number of female parents laying those eggs. The result of test in the second flight shows that the percentage of chromosome bridge in the neuroblasts of the third instar larvae of the first filial generation produced by female parents in the fourth to sixth day after flight is increased. The above results prove that the genetic materials of reproductive cells of female parents are slightly affected.