The introduction of an One Fungus–One Name (1F1N) concept has led to intensive discussions among taxonomists. Based on the Xylariaceae, a hyperdiverse family of Ascomycota with over 1300 species, the advantages and pitfalls of these nomenclatural changes and their consequences for taxonomy and applied mycology are discussed. Historically, in the Xylariaceae, an 1F1N concept had already been realised: The types of all important genera are conserved. Most teleomorphs were discovered long before the anamorphic stages, and the latter did not receive separate names, hence no drastic taxonomic changes are expected. The new nomenclature calls for abandonment of some illdefined anamorph genera, such as Muscodor. Other anamorph genera will be retained because their names refer to morphological symplesiomorphies that occur in several teleomorph genera. Various important taxa are only known from ancient specimens, and no DNA-based data are available. Much work still remains to be done to recollect these fungi, select epitypes, and settle their phylogenetic relationships. Until then, we recommend that taxonomic changes be applied at the suprageneric ranks whenever possible, to maintain nomenclatural stability.