Invasive growth or systemic infections by A. oryzae in healthy humans have never been reported. In a few cases, however, isolates identified as A. oryzae have been recovered from debilitated patients. A. oryzae has therefore low pathogenic potential but may, like many other harmless microorganisms, grow in human tissue under exceptional circumstances. Allergic diseases primarily caused by A. oryzae have been reported in few cases, but probably presuppose both a sensitivity to allergenic reactions and a massive exposure to conidia by inhalation. A. oryzae does not produce aflatoxins or any other cancerogenic metabolites. The absence of significant levels of mycotoxins in industrial products is regularly checked. We therefore consider A. oryzae an excellent host for the safe production of harmless products by recombinant strains.