The current biogeographic distribution of basidiomycete fungi that occur in the Greater Antilles is best understood according to ecological groups. For example, the distributions of obligate ectomycorrhizal associates of pine have a different history and origin than many of the saprotrophic fungi. Families and genera of saprotrophic fungi also differ in the extent of their geographic ranges, which is probably related to differences in their abilities to disperse and successfully colonize. Ectomycorrhizal associates of the native pine on the island of Hispaniola are primarily the same species as those found with related pines in the eastern U.S.A., but some are from Florida and the Gulf region and others represent disjunct populations of species found only in Idaho or western North America and Mexico. The western North American disjuncts may represent the remnants of an ancient distribution. The incipient island of Hispaniola was much closer to northern Central America between 65 and 40 million years ago. Other species may have originated during or after the Pleistocene. Approximately a third of the ectomycorrhizal fungi from Hispaniola are previously undescribed species or varieties. While most of the new ectomycorrhizal taxa associated with pine are closely related to species of eastern North America, a new species of Amanita from Puerto Rico has no known relatives in the subgenus. While some of the ectomycorrhizal fungi associated with tropical dicots (primarily species of Coccoloba and Pisonia) are also found in the Lesser Antilles, many are previously undescribed. Although there is no evidence of ectomycorrhizal fungi associated with tropical dicots forming symbioses with introduced pines in Puerto Rico, there is evidence of historical host-witching among basidiomycetes from Quercus in North America to Pinus occidentalis on Hispaniola. Saprotrophic fungi of wet and rain forests which have spores that are apparently fragile have mostly restricted distributions. Thirty-six percent of species and varieties in the Hygrophoraceae and 43% of species in the Entolomataceae are known only from the Greater Antilles, some from a single island. There are relatively few species in these families that are also found in the Lesser Antilles or South America, even though many of the lineages are thought to have arisen in South America. Hygrocybe section Firmae appears to have undergone a recent speciation in the neotropics. Pantropical species in these families comprise less than 4% of the total. The Entolomataceae have several disjunct species that are also found in Madagascar. Only a few species in the Greater Antilles are also found in the north temperate zone. Basidiomycetes of dry and moist forest habitats and those with durable spores are more likely to have broad geographic distributions. These include species of Pleurotus, Psathyrella, Coprinus, Schizophyllum, some polypore genera, and many gasteromycete and jelly fungi. At least ten of the polypore species that are new records for the Greater Antilles were previously known only from Africa or the paleotropics.