Aims: To determine the effect of mineral ions (e.g., Zn2+ , Cu2+ , and Fe2+ ) on the enhancement of fungal growth, total RNA, aflatoxin pathway gene expression, and production of aflatoxin and its precursor O -methylsterigmatocystin (OMST). Methods and Results: The influence of the metal ions, as a single or mixed treatments, was observed in submerged cultures of toxigenic Aspergillus flavus through changes in the fungal RNA or aflatoxin pathway gene (omtA) by reverse transcription-polymerase chain reaction (RT-PCR) levels, and also in fungal dry-weight accumulation, aflatoxin and OMST production. Conclusions: The ion treatments induced changes of fungal total RNA, mRNA levels, associate fungal growth, biosynthesis of aflatoxin and OMST, and enhanced expression of RT-PCR. Significance and Impact of Study: Demonstrates at the cellular and molecular level, the significant effects of metal ions on both fungal growth and production of aflatoxin.