The results of floral studies carried out by the author in 2002–2004 on 45 islands in the northern Gulf of Finland (Leningrad Region, Russia) are represented. The paper contains a brief account of earlier floral research in the islands, a general description of the islands' flora, as well as the checklist of vascular plant species recorded from the islands. The number of species in the islands varies depending on the size of each island, its location, human impact and effect of bird colonies on the flora. The main distinguishing features of the floras are as follows: relatively high species richness, numerous plant species growing at the limits of their distribution range, considerable proportion of maritime species including some Baltic and Fennoscandian-Baltic endemic and subendemic
plants.