During the last two decades, the natural ability of a common soil bacterium, Agrobacterium tumefaciens, to transfer deoxyribonucleic acid (DNA) to plants has been modified by scientists for use in the genetic engineering of many crop species into improved sources of food, fiber, and ornamentation. A scientific milestone in the genetic transformation of organisms occurred in recent years with the discovery that this bacterium can be manipulated to shuttle genes into fungi as well. The ease with which a rapidly increasing number and diversity of fungal species lend themselves to Agrobacterium-mediated transformation promises that genetically enhanced fungi will play a prominent role in a wide variety of novel industrial processes and applications.