The papers in this volume were presented at the 8th Workshop on Algorithms and Data Structures (WADS 2003). The workshop took place July 30–August 1, 2003, at Carleton University in Ottawa, Canada. The workshop alternates with the Scandinavian Workshop on Algorithm Theory (SWAT), continuing the tradition of SWAT and WADS starting with SWAT’88 and WADS’89. In response to the call for papers, 126 papers were submitted. From these submissions, the program committee selected 40 papers for presentation at the workshop. In addition, invited lectures were given by the following distinguished researchers: Gilles Brassard, Dorothea Wagner, Daniel Spielman, and Michael Fellows. Atthisyear’sworkshop,WingT.Yan(NelliganO’BrienPayneLLP,Ottawa) gave a special presentation on “Protecting Your Intellectual Property.” On July 29, Hans-Georg Zimmermann (Siemens AG, Munc ¨ hen) gave a seminar on “N- ral Networks in System Identi?cation and Forecasting: Principles, Techniques, and Applications,” and on August 2 there was a workshop on “Fixed Parameter Tractability” organized by Frank Dehne, Michael Fellows, Mike Langston, and Fran Rosamond. On behalf of the program committee, we would like to express our apprec- tion to the invited speakers and to all authors who submitted papers.