The eucaryotic microbes collectively called fungi were introduced in chapter 5. The profound importance of fungi stems primarily from their role in the earth's ecological balance and their impact on agriculture. To a lesser—but not minor— extent, the fungi are also medically significant, as agents in human disease, allergies, and mycotoxicoses (intoxications due to ingesting fungal toxins). Diseases resulting from fungal infections, primarily by yeasts and molds, are termed mycoses. In this chapter, we will survey the most prevalent mycotic infections, including systemic, cutaneous, and subcutaneous forms. Other topics to be covered include common respiratory allergies and diseases associated with fungal toxins.