This book constitutes the refereed proceedings of the 5th International Workshop on Distributed Computing, IWDC 2003, held in Kolkata, India in December 2003. The 32 revised full papers presented together with five invited papers were carefully reviewed and selected from a total of 105 submissions. The papers are organized in topical sections on distributed algorithms, internetworking and web, parallel and distributed systems, wireless and mobile networking, ad-hoc and sensor networks, learning and optimization, and optical networking