The Hymenochaetales are an order of fungi in the class Agaricomycetes. The order in its current sense is based on molecular research and not on any unifying morphological characteristics. According to one 2008 estimate, the Hymenochaetales contain around 600 species worldwide, mostly corticioid fungi and poroid fungi, but also including several clavarioid fungi and agarics. Species of economic importance include wood decay fungi in the genera Phellinus and Inonotus sensu lato, some of which may cause losses in forestry. Therapeutic properties are claimed for Inonotus obliquus ("chaga") and Phellinus linteus, both of which are now commercially marketed.

The Agaricomycetes are a class of fungi in the division Basidiomycota. The taxon is roughly identical to that defined for the Homobasidiomycetes by Hibbett & Thorn, with the inclusion of Auriculariales and Sebacinales. It includes not only mushroom-forming fungi, but also most species placed in the deprecated taxa Gasteromycetes and Homobasidiomycetes. Within the subdivision Agaricomycotina, which already excludes the smut and rust fungi, the Agaricomycetes can be further defined by the exclusion of the classes Tremellomycetes and Dacrymycetes, which are generally considered to be jelly fungi. However, a few former "jelly fungi", such as Auricularia, are classified in the Agaricomycetes. According to a 2008 estimate, Agaricomycetes include 17 orders, 100 families, 1147 genera, and about 21000 species. Modern molecular phylogenetic analyses have been since used to help define several new orders in the Agaricomycetes: Amylocorticiales, Jaapiales, Stereopsidales, and Lepidostromatales.