Several toxins have been implicated in Aspergillus fumigatus pathogenicity. Among these are gliotoxin, fumagillin, fumagatin, and helvolic acid. Recently we have identified a nuclear protein, LaeA, that regulates the production of all of these metabolites. Several criteria support the role of LaeA as a potent A. fumigatus virulence factor. Among these are a decreased ability of the laeA deletion strain (ΔlaeA) to cause fatal infections in the murine model, increased macrophage phagocytosis of ΔlaeA conidia and decreased ability of ΔlaeA to kill polymorphonuclear neutrophils [1]. Here we present our current knowledge of LaeA function and future directions of study of LaeA mechanism.