A total of 600 samples of 167 species of macro- and microlichens were collected mainly by Pauline Topham and Geoffrey Halliday on bottanical expeditions to Central East Greenland in thee years 1961, 1962, 1968, 1971 and 1980. Three of the species, viz., Caloplaca tornoensis Magnusson, thizocarpon pusillum Runem, and Verrucaria thalassina (Zahlbr.) Zsch. are additions to the known lichen flora of Greenland. The following eleven species have not previously been reported from East Greenland: Catillaria philippea (Mont.) Massal., Cladonia luteoalba A. Wilson & Wheldon, C. macroceras (Delise) Ahti, Coelocaulon divergens (Ach.) R.H. Howe, Diploschistes muscorum (Scop.) R. Sant., Leprocaulon subalbicans (Lamb) Lamb & Ward, Peltigera kristinssonii Vitik., Pertusaria octomela (Norman) Erichsen, Thizocarpon intermediellum Räsänen, Solorina saccata (L.) Ach. and Thelidium papulare (Fr.) Arnold.

Information is provided on climatic conditions at two meteorological stations situated in the area investigated. Thirtyeight collecting localities are listed, together with brief notes on their geology. The localities are situated between the southernmost part of Liverpool Land and Jameson Land, c. 70ÂN, and the middle of Lyell Land and Traill Ø, c. 73ÂN.

A survey is given of some important ecological, phytosociological and distributional characteristics for the lichen species, together with information on the presence of perithecia or apothecia.

Lichens of particular interest are discussed in the special part of the paper. A number of commonly used synonyms are listed in the Appendix.