This book constitutes the thoroughly refereed post-proceedings of the 5th International Bi-Conference Workshop on Agent-Oriented Information Systems, held in Melbourne, Australia in July 2003 at AAMAS 2003 and in Chicago, IL, USA in October 2003 at ER 2003. The revised full papers presented were carefully selected during two rounds of reviewing and improvement from a total of 36 submissions. The papers are organized in topical sections on information systems and applications; methodologies; and modeling, analysis, and simulation.