EN
During the production of the radiation source that used in radiotherapy may occur nuclear reactions are very important in terms of human health. ^{137}Cs is used in radiotherapy that consists of fission the ^{235}U core. Because of physical half-live of ^{137}Cs is 30 years, it is advantage for the radioactive half-lives. In this study, radionuclide production reaction cross section for ^{235}U (n,f)^{137}Cs is calculated with TALYS 1.6 nuclear simulation code that based on Monte Carlo.