Poroid Aphylloporales’ growth on Quercus mongolica in Northeastern China wasinvestigated during 1993-2004. The wood of the Mongolian oak seems to be good substratum forpolypores, and 75 species were recorded from the tree or its wood. Out of them 21 species (ca. 28%)are considered as rare species, 30 species (ca. 40%) as occasional species, and 24 species (ca. 32%) ascommon species. Ten species are the pathogens on the Mongolian oak. Most of the polypores werefound on other trees as well, but 14 species live exclusively on Q. mongolica. Poroid Aphylloporales’ growth on Quercus mongolica in Northeastern China was investigated during 1993-2004. The wood of the Mongolian oak seems to be good substratum for polypores, and 75 species were recorded from the tree or its wood. Out of them 21 species (ca. 28 % of species are considered as rare species, 30 species (ca. 40%) as occasional species, and 24 species (ca. 32%) ascommon species. Ten species are the pathogens on the Mongolian oak. Most of the polypores were found on other trees as well, but 14 species live exclusively on Q. mongolica.