Dillapiol was isolated from the essential oil of dill as a specitic inhibitor of aflatoxin G(1) production. It inhibited aflatoxin G(1) production by Aspergillus parasiticus with an IC50 value of 0.15 mu m without inhibiting aflatoxin B, production or fungal growth. Apiol and myristicin, congeners of dillapiol, showed similar activity with IC50 values of 0.24 and 3.5 mu m, respectively.