Ionizing radiation administered for cancer treatment or from nuclear plant accidents are two common causes of radiation exposure. Ionizing radiation exposure generates reactive oxygen species and free radicals, which cause oxidative stress. We previously reported that taurine contributes to the recovery from radiation-induced injuries, suggesting its potential as a radioprotector and radiation mitigator. However, the effect of taurine on radiation-induced gastrointestinal syndrome remains poorly understood. The aim of this study was to examine the effect of taurine tissue depletion on radiation-induced gastrointestinal syndrome. Mouse models of radiation-induced gastrointestinal syndrome were established in TauT+/+ and TauT-/- mice by whole-body X-irradiation. We examined the 30-day survival rate, as well as the crypt-villus structure and proliferation of proliferating cell nuclear antigen (PCNA) + cells in the small intestine. The survival rate of TauT-/- mice was significantly lower than that of TauT+/+ mice. The villi in the small intestine of TauT-/- mice were significantly shorter than those in TauT+/+ mice. Additionally, there were significantly fewer PCNA+ cells in TauT-/- mice than in TauT+/+ mice. These data demonstrate that taurine is a key regulator of crypt stem cells and plays an important regulatory role in intestinal cell survival, proliferation, and fate. Therefore, taurine may reduce radiation-induced gastrointestinal syndrome.