Studies of large and mainly recent collections of lichens and lichenicolous fungi led to the addition of 27 taxa to the flora of Belgium, Luxembourg and northern France: Arthonia coronata, A. mediella, Candelaria pacifica, Chaenothecopsis parasitaster, Dacampia cyrtellae, Dactylospora parellaria, Diplotomma epipolium var. parasiticum, Epigloea urosperma, Graphis betulina, Graphium aphthosae (also new to the Netherlands), Lepraria toensbergiana (also new to France), Lichenopeltella maculans (also new to France), Melaspilea bagliettoana, Miriquidica atrofulva, Mycocalicium subtile, Phaeopyxis punctum, Phaeosporobolus chlaroterae (also new to Norway), Placynthium posterulum, Pleospora physciae, Pronectria septemseptata, Sclerophora amabilis, Spiloma auratum, Stigmidium xanthoparmeliarum, Strangospora deplanata, Trapeliopsis wallrothii, Tylophoron hibernicum and Xanthoria ucrainica. 11 additional taxa were reported in recent publications: Buellia saxorum, Cladophialophora cladoniae, Fusicladium peltigericola, Graphis macrocarpa, G. pulverulenta, Laetisaria lichenicola, Lichenoconium aeruginosum, Ochrolechia mahluensis, Phoma ficuzzae, Trimmatostroma quercicola and Verrucaria rhizicola. New to Belgium: Echinodiscus lesdainii, Tremella hypogymniae; new to Luxembourg: Caloplaca arcis; new to France: Graphis macrocarpa, Laetisaria lichenicola, Lichenochora obscuroides, L. weillii, Lichenopeltella peltigericola. Additional notes are given on some rare and threatened macrolichen species. Arthonia digitatae and Placynthium stenophyllum have to be deleted from the checklist. The following new combinations are proposed: Alyxoria culmigena (Lib.) Ertz (basionym Opegrapha culmigena), A. ochrocincta (Werner) Ertz (O. ochrocincta), A. variiformis (Anzi) Ertz (O. variiformis), A. viridipruinosa (B. J. Coppins & R. Yahr) Ertz (O. viridipruinosa), Zwackhia bonplandii (Fée) Ertz (O. bonplandii), Z. circumducta (Nyl.) Ertz (O. circumducta), Z. prosodea (Ach.) Ertz (O. prosodea), Z. robusta (Vain.) Ertz (O. robusta) and Z. sorediifera (P. James) Ertz (O. sorediifera).