Budzisk nature reserve belongs to an old-growth forest Knyszyńska Large Forest complex. During the present study. 185 taxa of lichens, lichenicolous and saprobic fungi were recorded in the reserve. Seventy seven taxa of them are red-listed in Poland and NE Poland or are indicators of an old-growth forest. Consequently, the Budzisk reserve can be considered to be a biocentre of a diversity of lichens especially those characterislic of old-growth forests in NE Poland. During the study, the following rare and noteworthy species of lichens and allied fungi were found: <i>Absconditella lignicola, Acrocordia cavata, Biatora ocelliformis, Fellhanera gyrophorica, Fellhaneropsis vezdae, Micarea hedlundii, Mycocalicium subtile, Pertusaria pupillaris, Phaeopyxis punctum</i>, and <i>Stenocybe pullatula</i>. They have been recorted for the Knyszńska Large Forest for the first lime.