According to their origin, geomorphology and hydrology, the fresh/brackish-water bays and coastal lakes of the Southern Baltic coast can be treated as lagoons. They developed at the time of and as a result of the Atlantic (Litorina) transgression of the Southern Baltica. There are many publications about the origin and evolution of the lagoons and lakes along the Polish coast of the Southern Baltic (e.g. Przybyłowska-Lange, 1973a, b, 1974, 1979, 1981; Zaborowska, 1977; Zachowicz, 1977, 1985; Wypych, 1980a, b; Zachowicz et al., 1982; Bogaczewicz-Adamczak, Miotk, 1985a, b; Dąbrowski et al., 1985; Zachowicz, Zaborowska, 1985; Borówka et al., 2001a, b, 2002). Nevertheless, the origin of the lagoons has not been fully explained. In the light of present-day information the results of earliest investigations often need to be reinterpreted. The aim of this work was the correlation of the published and unpublished pollen and diatom diagrams from Late Pleistocene and Holocene sediments of the Southern Baltic lagoons, and their relation with radiocarbon dating. The pollen and diatom diagrams from the area of north-east Germany and the Curonian Lagoon (Kabailiene., 1999; Jahns, 2000; Kaiser et al., 2000; Endtmann, 2002; Bitinas et al., 2002) have been used for comparison. For the palynological sites, the local pollen assemblage zones (L PAZ) have been identified according to Janczyk-Kopikowa (1987). Comparison of the biostratigraphical data allowed us to define the approach time of the formation of the lagoons in their present-day position on the coast as well as to determine the periods of an accelerated sea-level rise and increased frequency of storm surges (so-called marine transgression phases) when the investigated areas had been under the direct influence of the sea. Such influences are visible about 7000, 6000, 5000 and 4000 years BP. This period of marine influences, about 1000-year long, corresponds very well to the same period of climate oscillations mentioned by Stuiver and Braziunas (1993), Stuiver et al. (1995) and Chapman and Shackelton (2000). The influence of the sea in the Post-Litorina period was associated mainly with the inflow of sea water through more or less developed barriers, so they are not synchronous.