Aa a result of ratification of the Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea, Poland is obliged to perform continuous monitoring of water run-off to the Baltic Sea. Highly industrialised and urbanized areas along the Odra River severely threaten the environment in the Szczecin Bay. The authors present their own model for appraisal of the aquatic environment of the Szczecin Bay, based on chemical and bacterial indicators as well as on immunological, genetic and biochemical biomarkers in fish and/or mollluscs. The model has been developed by the Faculty of Natural Sciences of Szczecin University.