The effect of ginseng saponin on aflatoxin(AF) production by Aspergillus parasiticus NRRL2999 and the mutagenicity of produced aflatoxin. The production of aflatoxin were decreased by the addition of ginseng saponin and the most effective concentration was 0.05%. The ratio of aflatoxin $B_{1}$ and aflatoxin $G_{1}$ were not changed by the addition of ginseng saponin. For the nutagenicity test, Ames method were adopted. Mutagenicity of mycelial aflatoxin was decreased by the addition of ginseng saponin on TA98, but not changed on TA100. Mutagenicity of excreted aflatoxin to broth was slightly increased by the saponin on TA98, but decreased on TA100.