Records of 26 vascular plant species from the territory of Sopron Mountains (16 species) and Sopron Basin (11 species) are presented. Our field works (between 2014 and 2020) focused on some localities at the eastern and southern parts of the region. Tetragonolobus maritimus is new for the Sopron Mts, whereas Ajuga chamaepithys and Lycopsis arvensis are new for the Hungarian part of the hills. Some protected plants like Agrostemma githago, Gentianopsis ciliata and Sesleria uliginosa were rediscovered in the region. Comments about all species and their local chorology are added. A remarkable degradation process of bogs around Harka village, caused mainly by insufficient water supply of meadows, was observed. The spread of occurrences of several naturalized weed such as Aegilops cylindrica, Galium parisiense, Geranium rotundifolium, Kochia scoparia, Lepidium virginicum, Oenothera salicifolia, Sagina apetala subsp. apetala and Verbascum lychnitis was noticed. The most surprising observations refer to Galium parisiense; the spread of the species by transport had no precedent in Hungary before.