Abstract: Although a variety of organic compounds bearing thiomorpholine ring system possess many interesting pharmacological properties, simplier derivatives carrying this ring system have scarcely been investigated in the field of drug research. In our preliminary. study of antiradiation drugsi it has been shown that-β-mercaptoethylamine, Ⅵ, and some simple amino derivatives Ⅶ and Ⅷ exhibited prophylactic activities against ionization radiation. These results gave us an impetus to study whether thiomorpholine (which may be regarded as the cyclic ether of mercatoethylamine) or its derivatives related to Ⅵ, Ⅶ and Ⅷ would show promise as antiradiation drugs.In the present paper the synthesis of a series of mercaptoethylamine derivatives carrying thiomorpholine moiety Ⅸ, some xanthates Ⅹ and amino derivatives of Ⅺ, Ⅻ related to Ⅶ and Ⅷ was reported.