An RNAseq study was conducted to determine changes in gene expression during co-culture of a toxigenic (Tox) Aspergillus flavus isolate and non-aflatoxigenic (Non-tox) biocontrol A. flavus isolate. Tox 53 isolate and Non-tox 17 isolates were grown separately and co-cultured for 30 and 72 h. RNA was extracted and 150 bp paired end sequencing reads were generated using Illumina NextSeq 500. When Non-tox isolate 17 and Tox 53 isolate grew together in co-culture, acutely deadly and carcinogenic aflatoxin was not produced. The goal of the study was to identify candidate genes that regulate aflatoxin production during the biocontrol interaction.