This research study examined the prevalence of symptoms and identified risk factors for reported symptoms among a group of Army Gulf War (GW) veterans. A survey was mailed to all members of the Ft. Devens cohort in 1997, representing the third assessment of a group that consisted of 2949 US Army soldiers deployed to the Gulf, and was studied initially in 1991. A total of 1290 subjects responded to the mailed survey; aggressive follow-up methods to address non-response bias were employed. Subjects were classified as having multisymptom illness if they reported symptoms from at least two of three symptom categories (fatigue, mood-cognition, musculoskeletal). Sixty percent of the respondents met criteria for multisymptom illness. Female gender, lower levels of education, psychological symptoms, self-reported use of a medical clinic in the Gulf, ingestion of anti-nerve gas pills (pyridostigmine bromide), anthrax vaccination, tent heaters, exposure to oil fire smoke, and chemical odors were significantly related to multisymptom illness in logistic regression analyses. Analyses in which subjects were stratified by level of psychological symptoms revealed different sets of GW-service environmental exposures and suggest that subgroups of GW veterans may have different sets of risk factors.