We sought to assess quality of life and health-services utilization variables in persons with symptoms suggestive of multiple chemical sensitivity/idiopathic environmental intolerance (MCS/IEI) among military personnel. We conducted a cross-sectional telephone survey of a population-based sample of Persian Gulf War (PGW) veterans from Iowa and a comparison group of PGW-era military personnel. A complex sample survey design was used, selecting subjects from four domains: PGW active duly, PGW National Guard/Reserve, non-PGW active duty, and non-PGW National Guard/Reserve. Each domain was substratified by age, gender, race, rank, and military branch. The criteria for MCS/IEI were developed by expert consensus and from the medical literature. In the total sample, 169 subjects (4.6%) of the 3695 who participated (76% of those eligible) met our criteria for MCS/IEI. Persons who met the criteria for MCS/IEI more often reported the following than did other subjects: more than 12 days in bed due to disability, Veteran's Affairs disability status, Veteran's Affairs disability compensation, medical disability, and unemployment. MCS/IEI cases also had higher outpatient rates of physician visits, emergency department visits, and inpatient hospital stays. Subjects who met the criteria for MCS/IEI more often reported impaired functioning on each Medical Outcomes Study 36-Item Short Form subscale, compared with those who did not meet the criteria. We concluded that although the diagnosis of MCS/IEI remains controversial, the persons who met our criteria for the disorder are functionally impaired.