BackgroundThe aim was to determine the prevalence of chronic fatigue syndrome (CFS), chronic fatigue and fibromyalgia in UK military personnel after the Gulf War 1990–1991.MethodA two-phase cohort study was used. Three randomly selected subsamples identified from a population-based cross-sectional postal survey of over 10 000 current and ex-service UK military personnel (Gulf veterans were those deployed to the Gulf War 1990–1991; non-Gulf veterans were Bosnia peacekeepers 1992–1997 and those on active duty during the Gulf War 1990–1991 but not deployed) were recruited. Their disability status was assessed using the Short Form 36 physical functioning scale; Gulf veterans who reported physical disability (n=111) were compared with non-Gulf (n=133) veterans who reported similar levels of physical disability. Screening for known medical and psychiatric conditions was conducted to exclude medical explanations for disability and symptomatic distress. Standardised criteria for CFS, chronic fatigue and fibromyalgia were used.ResultsDisabled Gulf veterans were more likely to be overweight, have elevated γ-glutamyl transferase levels and screen positive for hypertension. There were no other clinically significant differences in clinical markers for medically explainable conditions. Disabled Gulf veterans were more likely than similarly disabled Bosnia and Era veterans (adjusted odds ratio 7.8, 95% confidence interval 2.5–24.5) to meet the criteria for CFS. Rates for other medically unexplained conditions were not significantly increased.ConclusionsSymptoms in keeping with CFS account for a significant part of the symptomatic distress in Gulf veterans.