Phanerochaete is a genus of resupinate homobasidiomycetes that are saprophytic on woody debris and logs. Morphological studies in the past indicated that Phanerochaete is a heterogeneous assemblage of species. In this study the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA was used to test the monophyly of the genus Phanerochaete and to infer phylogenetic relationships of the 24 taxa studied. Maximum parsimony, maximum likelihood, and Bayesian analyses do not support the monophyly of the genus. However, a core group of species represented by Phanerochaete velutina, P. chrysosporium, P. sordida, P. sanguinea and others are closely related and group together in a clade. Other common Phanerochaete species including Phanerochaete rimosa, P. chrysorhiza, P. omnivora, P. avellanea, P. tuberculata, P. flava, and P. allantospora, however, do not cluster with the core Phanerochaete group.