Food additives such as turmeric (Curcuma longa), and active ingredient curcumin (diferuloyl methane), asafoetida (flavouring agent), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and ellagic acid were found to inhibit the mutagenesis induced by aflatoxin B1 (AFB1) (0.5 microg/plate) in Salmonella tester strains TA 98 and TA 100. Turmeric and curcumin, which were the most active, inhibited mutation frequency by more than 80% at concentrations of 2 microg/plate. Other food additives were also significantly effective. Dietary administration of turmeric (0.05%), garlic (0.25%), curcumin and ellagic acid (0.005% each) to rats significantly reduced the number of gammaglutamyl transpeptidase-positive foci induced by AFB1 which is considered as the precursor of hepatocellular neoplasm. These results indicate the usefulness of antioxidant food additives in ameliorating aflatoxin-induced mutagenicity and carcinogenicity.