This book constitutes the thoroughly refereed postproceedings of the 5th International Workshop on Open MP Application and Tools, WOMPAT 2004, held in Houston, TX, USA in May 2004. The 12 revised full papers presented were carefully selected during two rounds of reviewing and improvement. The papers are devoted to using Open MP for large scale applications on several computing platforms, consideration of Open MP parallelization strategies, discussion and evaluation of several proposed language features, and compiler and tools technology.