A mutagenic evaluation of captan, folpet, captafol, dichlofluanid and related compounds was carried out using the Salmonella/mammalian microsome test using strains TA102 and TA104. These strains contain A-T base pairs at the site of the mutation in contrast to the other Salmonella tester strains that detect mutagens damaging G-C base pairs. In addition, the excision repair system of the TA102 strain is still intact. Captan and folpet were mutagenic in strain TA104, captafol was mutagenic in strain TA102, whereas the remaining test compounds (dichlofluanid, tetrahydrophthalimide and thiozolidine-4-carboxylic acid) were not mutagenic in either strain. In conclusion, we consider it of value to add these two strains to those already used in the Ames test in order to increase confidence in our ability to detect mutagens and to shed further light on their mechanism of action.