The purpose of this study was to compare health status and disease profiles of ambulatory patients in specific Veterans Administration (VA) and civilian healthcare settings. A random sample of 2425 male veterans seeking care at 4 Boston-area VA outpatient clinics, who took part in the Veterans Health Study (VHS) in 1993-1995, were compared to 1318 male patients seeking civilian outpatient care in 3 major metropolitan areas covered in the Medical Outcomes Study (MOS) in 1986. The MOS sampled patients who had 1 of 5 conditions--hypertension, noninsulin-dependent diabetes, recent myocardial infarction, congestive heart failure, or depression. These 2 samples were age adjusted and compared in terms of the SF-36 Health Status/Quality of Life measures, and a list of 100 clinical variables (diagnostic, symptom, and medical event reports) collected with comparable instruments by a trained clinical observer. Individual odds ratios (VHS to MOS) were calculated for each measure and clinical variables. SF-36 measures of patient health in the VHS were lower than those in the MOS by more than one half of a standard deviation (SD) on 4 of 8 scales, by more than one quarter of a SD on the other 4, by 58% of a SD on the physical health summary scale, and by 37% of a SD on the mental health summary scale (P < .0001 in all cases). The median odds ratio was 2.2 among the SF-36 scales and 1.9 among clinical variables. Outpatients in the 4 VA clinics had more than twice the illness burden than did patients in the MOS. Current economic condition and service-connected disability explain most, if not all, of the differences. The differences were clinically and socially meaningful and would be consistent with substantially higher expected healthcare use.