The endemic mycoses are diverse group of fungi that share several characteristics. They are able to cause disease in healthy hosts, they each occupy a specific ecologic niche in the environment, and they exhibit temperature dimorphism, existing as molds in the environment at temperature of 25 degrees C to 30 degrees C, and as yeasts, or spherules in the case of coccidioidomycosis, at body temperatures. This article discusses histoplasmosis and blastomycosis. Sporotrichosis, which differs in that it is usually a localized lymphocutaneous infection, is included because it shares the characteristics of endemic mycoses.