We studied the spatial distribution of annelids in the intertidal zone of two beaches (Engenho d'Agua and Sao Francisco) in Sao Sebastiao Channel, southeastern Brazil, from August 1995 through July 1996. This region is commonly affected by oil spills and sewage waste. The substratum of the two beaches is composed of a mixture of sand and rock fragments. We established three levels (100 m(2)) in the intertidal zone of each study sited lower, intermediate, and upper. In general, species richness increased from upper towards lower levels. The distribution of species at Engenho d'Agua was more homogeneous than at Sao Francisco. Only some individual spatial patterns were recognised at Sao Francisco. The most abundant polychaete species at Engenho d'Agua (Nematonereis hebes, Timarete filigera, and Scyphoproctus djiboutiensis) occurred in the intermediate and lower levels. The upper level of Sao Francisco was characterised by a peak of opportunists, with a large number of individuals but few dominant species (Capitella sp., Scolelepis squamata, Laeonereis acuta, and the oligochaete Tubifex sp).654323331