This book constitutes the refereed proceedings of the 5th International Workshop on Databases in Networked Information Systems, DNIS 2007, held in Aizu-Wakamatsu, Japan in October 2007. Focusing on data semantics and infrastructure for information management and interchange, the papers are organized in topical sections on geospatial decision-making, Web data management systems, infrastructure of networked information systems, and Web query and web mining systems.