Abstract: The synthesis of 2-substituted-1,3-thiazanes is reported. These compounds were prepared by condensation of 3-mercaptopropylamine hydrobromide and aldehydes or ketones in the presence of triethylamine. All the synthetic compounds were tested for radioprotective activity in mice. Preliminary results showed that only 2-methyl-2-ethyl-1,3-thiazane hydrochloride and 2-phenyl-1,3-thiazane hydrochloride exhibited radio-protective action. The protection of the others were not significant.