This report presents results of the GIWA assessment of the East China Sea region, which is one of the largest marginal seas in the world. This region receives tremendous inflow of freshwater and terrestrial sediments, predominantly from China's mainland. The region is characterized by a large population and rapid economic development. The natural landscape in the region's drainage basins has been greatly modified by the development and expansion of agriculture, the construction of dams as well as urbanization. Aquaculture and coastal area reclamation alter natural wetlands and destroy spawning and nursery grounds in the East China Sea. Overexploitation of fish, eutrophication and habitat modification are of particular concern in the region. The past and present status and future prospects are discussed, and the transboundary issues are traced back to their root causes. Policy options that aim to address these driving issues in order to significantly improve environmental quality and secure the region's future prosperity are recommended