Protocol describes the general procedure for creating mutations in the DNA of Drosophila by exposure to X-rays. Irradiation of cells with X-rays creates double strand breaks (DSBs) in DNA. Mutations introduced in the DNA of germ line cells (sperm) are propagated by mating the exposed males to virgin females. The progeny of this cross can be mated to each other so that a percentage of the subsequent offspring will have two copies of the same mutant allele. - [Read X-Ray Mutagenesis of Drosophila Protocol]