The papers in this volume were presented at the Third Workshop on Algorithms and Data Structures (WADS '93), held in Montreal, Canada, August 1993. The volume opens with five invited presentations: "Computing the all-pairs longest chains in the plane" by M.J. Atallah and D.Z. Chen, "Towards a better understanding of pure packet routing" by A. Borodin, "Tolerating faults in meshes and other networks" (abstract) by R. Cole, "A generalization of binary search" by R.M. Karp, and "Groups and algebraic complexity" (abstract) by A.C. Yao. The volume continues with 52 regular presentations selected from 165 submissions, each of which was evaluated by at least three program committee members, many of whom called upon additional reviewers.