Abstract
Microorganisms, in special fungi, have been a most significant source of drugs for therapeutic use. Endophytic fungi, which reside in the tissues of virtually all living plants and present important interaction with the host, because of what appears to be their contribution to the host plant, may produce a plethora of substances of potential use as medicine. Medicinal plants have been recently subject of investigations related to their endophytic fungi and their secondary metabolites. Besides the possibility of producing the same substance as the host plant or a bioactive analogous, these microorganisms may synthesize novel molecules with antibiotic, antimycotic, immunosuppressant, anticancer, and other activities.