This volume contains the proceedings of the fifth International Workshop on Distributed Algorithms (WDAG '91) held in Delphi, Greece, in October 1991. The workshop provided a forum for researchers and others interested in distributed algorithms, communication networks, and decentralized systems. The aim was to present recent research results, explore directions for future research, and identify common fundamental techniques that serve as building blocks in many distributed algorithms. The volume contains 23 papers selected by the Program Committee from about fifty extended abstracts on the basis of perceived originality and quality and on thematic appropriateness and topical balance. The workshop was organizedby the Computer Technology Institute of Patras University, Greece.