This book constitutes the thoroughly refereed post-proceedings of the 5th International Workshop on Formal Approaches to Software Testing, FATES 2005, held in Edinburgh, UK, in July 2005 in conjunction with CAV 2005.

The 13 revised full papers presented together with 1 work-in-progress paper were carefully selected from 38 initial submissions. The papers address formal approaches to testing and use techniques from areas like theorem proving, model checking, constraint resolution, program analysis, abstract interpretation, Markov chains, and various others. These techniques are combined with traditional approaches to testing.