This article describes vegetation history and plant succession in Lakes Kojle and Perty (NE Poland) and in the surrounding peatlands during the last 9400 cal. BP. Vegetation changes were reconstructed based on high-resolution plant macrofossil analysis of three sediment cores. The changes in vegetation and the course of succession found in the studied lakes and peatlands resulted largely from regional climate changes. Climate cooling that took place approximately 5000 cal. BP resulted in an increase in Picea abies cover in the vicinity of the lakes, as well as in the appearance of Nuphar pumila and Potamogeton alpinus in the lakes. A further increase in Picea abies approximately 3500 cal. BP coincided with the development of an ombrotrophic bog at one site. During the period under study, the aquatic plant species that persisted for the longest time at one site were Najas marina and Nymphaea alba, and the shortest-term residents were Potamogeton spp.