Technical Abstract: The laeA gene encodes a nuclear protein that governs production of multiple fungal secondary metabolites. We examined the effects of laeA deletion in an Aspergillus flavus strain. Compared to wild type, expression of genes involved in secondary metabolism, conidiation and hydrophobicity was drastically reduced, but expression of genes involved in primary metabolism was decreased to a lesser extent. Dependent on medium composition, the laeA deletion strains exhibited varied morphological phenotypes. Asexual development such as formation of conidiophores and elongation of conidial chains was altered along with other physiological changes. Contrary to what was reported previously we found that the laeA deletion strains expressed low levels of aflR but were unable to produce aflatoxins or their precursors. The aforementioned defects were remediated in laeA addback strains. Our results suggest that loss of laeA exerts pleiotropic effects on expression of genes involved in development and secondary metabolite biosynthesis.