The concentrations of organochlorine pesticides, PCBs, and PCDD/Fs were measured in sediment samples collected from the Gulf of Gdansk, the Gdansk Deep, the Vistula Lagoon and the off-shore waters in the southern Baltic Sea. The determinations were conducted in the fraction <63 µm. The highest levels of pollutants were found in sediments from the Gulf of Gdansk and the Gdansk Deep. In these sediments, concentrations of pp′-DDT and its metabolites (pp′-DDE and pp(prime or minute)-DDD) ranged from 2 to 11 µg/kg dw. Concentrations of HCB were between 0.1 and 1.0 µg/kg dw. Concentrations of the sum of α-, β-, γ-HCH were between 0.3 and 2.58 µg/kg dw. Concentrations of marker PCBs ranged from about 2 to 11 µg/kg dry weight. Total TEQ PCDD/F/dl-PCB values in the studied samples varied between 1 and 18 ng/kg dw. The data were evaluated in terms of ecotoxicological criteria based on the environmental impact of the pollutant effects. The research indicated that in the sediment from the southern Baltic Sea, the PCDD/F and PCBs occurred at concentrations which could be dangerous to marine organisms.