4th International Verification Workshop Bernhard Beckert and Gerwin Klein (eds.) The VERIFY workshop series aims at bringing together people who are interested in the development of safety and security critical systems, in formal methods, in the development of automated theorem proving techniques, and in the development of tool support. Practical experiences gained in realistic verifications are of interest to the automated theorem proving community and new theorem proving techniques should be transferred into practice. The overall objective of the VERIFY workshops is to identify open problems and to discuss possible solutions under the theme "What are the verification problems? What are the deduction techniques?". This volume contains the research papers presented at the 5th International Verification Workshop (VERIFY'08) held August 10-11, 2008 in Sydney, Australia.