This study studied a sample of the 28,968 Iowans from the National Guard, Reserve, or active component who were on active duty during the Gulf War. A stratified random sample selected 4,886 subjects of whom 3,695 (76%) completed a structured telephone interview. Participants were asked about symptoms, health status, and exposures during the GW. Compared to those who did not deploy, personnel deployed to the Gulf reported significantly higher prevalence rates of symptoms of depression, PTSD, chronic fatigue, cognitive dysfunction, bronchitis, asthma, fibromyalgia, alcohol abuse, anxiety, and sexual discomfort. Most of the self-reported GW exposures were significantly related to many of the medical and psychiatric conditions. Personnel who served in Iraq, Saudi Arabia, or Kuwait were significantly associated with depression, cognitive dysfunction, and fibromyalgia, compared with those who were stationed elsewhere in the theater. The authors discuss the several possible interpretations of the associations found. They note that their study included a wide range of diagnoses more likely to be evaluated in outpatient settings, an advantage over other studies which used hospitalization data. Limitations of the study are: the possibility that a study of Iowans may not be generalizable; internal validation of responses was not done; medical conditions are based on self-reports of the participants and they have not been validated by objective physical or laboratory findings; and, the multiple comparisons in the analysis could have revealed statistically significant relationships by chance alone.