Eleven deletions were obtained in the rad(2)201 radiosensitivity gene region and the 41-45B4 fragment duplication in the Y chromosome were made by using chromosome rearrangements that transfer the material of the 44F - 45D site of chromosome 2 in Drosophila melanogaster to heterochromatin. The locus rad(2)201 was mapped in thin band region 45B3 by using these rearrangements and 13 deletions isolated before. Analysis of the complementation of the rad(2)201G1 radiosensitivity mutation by lethals and chromosome rearrangements in the 44F2-3; 45C5-6 region did not reveal any lethal alleles of this gene. The translocation T(Y;2)G6 was isolated; in this translocation, the change of the rad(2)201 gene expression causes high sensitivity of rad(2)201G1/T(Y;2)G6 heterozygotes of the initiation of the radiation-induced morphoses, while the survival rate of individuals remains at the level of wild-type flies.