1 . This dissertation attempts to present a first compilation of the lichen flora of the inner dry valleys of the Alps. As a basis for the research the author has spent during the years 1971 - 1977 at least 250 days in outdoor investigations in various inner dry valleys of the Alps collecting about 6,000 specimens from dry, hot habitats in the area 2. In the introduction to the thesis some indications are given of the special ecological conditions in the inner dry areas of the Alps by means of the following catchwords : subcontinental climatic type, lack of precipitation, low humidity of the atmosphere, comparatively many hours of sunshine by the lack of cloudiness and mist, direct south-exposition of the one side of the valley slopes due to west-east-course of the inner dry valleys, strong winds, human influence. There follows a short characterisation of the local research area (VINSCHGAU, WALLIS, AOSTA-TAL, VELTLIN, VIRGENTAL in Ost-tirol) and some remarks concerning the various lichen elements of the inner dry valleys of the Alps. 3. The main part of the thesis consists of a first compilation of 124 lichen species collected in dry, hot sites of the research area. Besides general remarks on taxonomy, morphology, ecology and distribution of the species detailed statements are given concerning the localities within the research area. For most of the lichens distribution maps are added. In order to render the most effective control only those localities are cited, which are verified by specimens from the herbarium of the author or in rare cases by specimens from other collections. 4. Noteworthy results: For a number of species, collected till now only from few localities (in some cases only one locality!), the research has brought numerous new localities (see Buellia buellioides, Buellia subsquamosa, Caloplaca microphyllina, Lecidella lacteola, Parmelia ulophyllodes, Physcia strigosa, Physconia petraea, Solorinella asteriscus, Toninia albomarginata) . There were also noteworthy finds of lichen species hitherto known only in other districts, especially in the Mediterranean area, which are scarcely or not at all collected in the inner dry valleys of the Alps, such as Caloplaca conglomerata. DipVosch.istes actinostomus, Diploschistes ocellatus, Fulgensia desertorum, Lecanora riparti, Lecidella sarcogynoides, Leptogium hildenbrandii, Parmelia stictica, Peltula obscurans var. obscurans, Peltula obscurans var. hassei, Physcia his- pidula, Physciopsis adgluttnata, Physconia grisea ssp. lilacina. Psora albilabra. Especially remarkable are the new localities of Peltula placodizans (up to now only known from North America !) and Parmelia soredians ( new to Central Europe). Among the various finds of Physcia constipata there was one with apothecia. Numerous localities of dry hot habitats are given for the lichen species Dimelaena oreina, Lecidella inamoena and Rhizoplaca chrysoleuca, which have their typical distribution in alpine regions and descend to lower regions only in dry areas. 5. On the advice of Prof. J. POELT a new combination was made: Buellia buellioides (Metzler ex Arnold) Buschardt nov. comb. Basionym: Rinodina buellioides Metzler ex Arnold. 6. New taxa were not produced