Abstract Amides of thiophosphoric acid were studied, in order to initiate correlations of mutagenicity with structure, by use of a modified Ames assay. Representative thiophosphoramides of the structure (XArNH) 3PS were not mutagenic, irrespective of whether X was a reference hydrogen atom, an electron-withdrawing, or an electron-donating group. One phosphoramidothioate of the structure (2, 4-X2ArNH) P (S)(OCH2CH3) 2 ...