Fungi are eukaryotic organisms that include examples such as yeasts, molds, mushrooms, rusts, rots and smuts. They can cause disease in humans and plants, as well as produce antibiotics that can cure microbial infections. Some types degrade decaying material and return nutrients to the ecosystem. We have sequenced several examples of the various fungal types at The Genome Institute. These include plant pathogens, yeasts, and human pathogens. The pathogen data aids in our understanding of the host-parasite relationship, whether plant or animal, and how the infective stages of the fungi studied manage to invade and maintain themselves. The yeast data increases our understanding of this important model system and allows analysis of the genetic basis and evolution of phenotypic variation present in natural populations.