These documents present the first trial version of the One System Inventory (OSI) information on the Eastern Nile: meant to serve as a regional knowledge-base across Egypt, Ethiopia and Sudan. The information is organized into a summary report and four more detailed annexes on the four main trans-boundary sub-basins of the Eastern Nile (Abbay-Blue Nile, Baro-Akobo-Sobat-White Nile, Tekeze-Setit-Atbara, and Main Nile). The work benefited from previously compiled national thematic OSI reports on environment, socio-economics and water in 2006 and the OSI synthesis reports in 2007, as well as from comments and suggestions received from regional workshops and meetings. This Report was subsequently updated and revised.