We present a checklist for Moshchny Island (Leningrad Region, Russia). The documented lichen biota comprises 349 species, including 313 lichens, 30 lichenicolous fungi and 6 non-lichenized saprobic fungi. Endococcus exerrans and Lichenopeltella coppinsii are reported for the first time for Russia; Cercidospora stenotropae, Erythricium aurantiacum, Flavoplaca limonia, Lecidea haerjedalica, and Myriospora myochroa for European Russia; Flavoplaca oasis, Intralichen christiansenii, Nesolechia fusca, and Myriolecis zosterae for North-Western European Russia; and Arthrorhaphis aeruginosa, Calogaya pusilla, and Lecidea auriculata subsp. auriculata are new for Leningrad Region. The studied lichen biota is moderately rich and diverse, but a long history of human activity likely caused its transformation, especially the degradation of forest lichen biota. The most valuable habitats for lichens in Moshchny Island are seashore and dune communities which definitely deserve protection.