The vegetation of the Eemian interglacial and Early Vistulian glaciation was reconstructed on the basis of pollen analysis, biogenic and mineral-biogenic sediments from the Żabieniec Południowy locality. It was revealed that the present-day fossil reservoir was formerly a lake existing continuously from the decline of the Warta stadial (LG MPG) to the end of the Early Vistulian (EV4). The upper Plenivistulian age of top sediments, previously accepted on the basis of the radiocarbon date 24 200 ± 350 yrs BP (uncalibrated), was not confirmed by pollen analysis. In the pollen record from the nearby Żabieniec mire a break in biogenic accumulation corresponding to the Lower and Middle Plenivistulian was discovered. In view of the character of Plenivistulian morphogenesis in that area it appears that the deposits of both basins illustrate the development of one large melt-out depression during the whole postglacial period.