Macrofauna community structures were investigated in the Pomeranian Bay (Southern Baltic Sea) in relation to important prevailing abiotic and trophic factors. Quantitative grab samples were collected at 34 sites at depths between 6 and 30m in 1993/94. 45 species were identified. Mya arenaria, Macoma balthica and Marenzelleria viridis are the most important species with respect to biomass. Mean total biomass values decreased from about 100 g AFDW/m 2 in the southwest of the bay (Oder Mouth) to only about 10 g AFDW/m 2 in the North (Arkona Basin). Multivariate analyses suggest distinct assemblages within the shallow bay and at the slope to the adjacent deeper zones. Loose structuring was found for communities of the shallow parts. They all are dominated by filter-feeders. Surface deposit-feeders are dominant at the northern boundary of the study area adjacent to the Arkona Basin. The small range of sediment variation could not explain distribution pattern of species with a large tolerance for sediment parameters. Physical disturbance and available food supply are proposed to be important in structuring the benthic community. The high biomass values in the southwest of the bay are thought to reflect the high anorganic and organic loads from the Oder River.