I would like to thank The Honorable Bernard Rostker, Special Assistant for Gulf War Illness, for sponsoring this review. I am indebted to Jack Heller, Ph.D., and Jeffrey Kirkpatrick, M.S., of the U.S. Army Center for Health Promotion and Preventive Medicine for their prompt assistance to all my requests for data and references. I appreciate the useful comments of Mike Hix, M.S., and Ross Anthony, Ph.D., of RAND in reviewing this report. I wish to thank Arthur Upton, M.D., of UMDNJ--Robert Wood Johnson Medical Center and Steven Colome, Sc.D., of Integrated Environmental Science for reviewing this document; their many suggestions have improved this report. However, the content and conclusions remain the sole responsibility of the author.