(1) The influence of organic sewage pollution on the macrobenthic community structure of a shallow inshoreregion was studied in the South of Kiel Bay (Baltic Sea). (2) The sandy bottom bears 3 associations withinthe pollution gradient. They can be characterized by: (a) Capitella capitata and Oligochaeta (50-100 m distancefrom the sewage outlet), (b) Pygospio elegans (200-ca. 700 m) and (c) Bathyporeia sarsi (>700 m). They haveno distinct borders but resemble rather a continuum. (3) In the less affected reaches the influence of biologicalsubstrate structure becomes more evident. Distinct associations can be distinguished. (4) The combination oflife forms, number of spp, diversity and other community features depend on the degree of the substrate'sspatial heterogenity in a characteristic way. They are also strongly influenced by the extent of pollution. (5)The inshore benthic macrofauna provides an important contribution to the self purification of the wholeecosystem by transforming particulate organic matter to available fish food. Abundance and biomass aremultiplied due to sewage sedimentation. This process creates the danger of accumulation of poisonoussubstances in addition to the eutrophication problem. (6) More highly diverse systems (e.g. mussel beds)resist better those factors which directly influence the evenness of the community. The ecological bufferconsists of many specialized competitors and predators. Systems low in diversity (e.g. sand) react much morestrongly to disturbances of this type. (7) Faunal composition, evenness, species richness, population densityand biomass of the communities are suitable parameters of an ecological method for the early recognition ofenvironmental stress.