Pain in the joints and other areas has been a frequent complaint among veterans of Operation Desert Storm who are experiencing unexplained illness. We characterized the rheumatic manifestations of a group of veterans of the Persian Gulf War who were referred to a rheumatology clinic. Consecutive South Texas veterans of the Persian Gulf War who were referred for evaluation of rheumatic manifestations underwent a comprehensive evaluation of their musculoskeletal symptoms, pain, and health related quality of life. Of 928 veterans evaluated in a screening clinic for unexplained symptoms, 145 had rheumatic manifestations (15.6%) and were referred to a rheumatology clinic. The most common diagnosis was fibromyalgia, present in 49 patients (33.8%), followed by various soft tissue problems in 25 (17.2%), nonspecific arthralgias in 14 (9.6%), and clinical or radiographic osteoarthritis in 16 (11.0%). In 39 patients (26.9%), no symptoms were present at the time of the evaluation, a careful musculoskeletal examination and laboratory tests were normal, and no diagnosis was possible. Two patients had Reiter's syndrome. Four had a positive rheumatoid factor and 3 had antinuclear antibodies, but none of these had clinical evidence of rheumatoid arthritis or systemic lupus erythematosus. Pain was present in nearly all patients and was widely distributed, with no body area spared in this group of patients. The most frequent painful areas were the knees in > 65%, the lower back in > 60%, the shoulders in 50%, and the hands and wrists in 35%. Widespread body pain was present in 65.1% of the veterans. Average values of all 8 scales measured by the SF-36 health survey were below the 25th percentile of published national norms, with pain and the number of nonarticular rheumatic symptoms explaining most of the decreased health related quality of life in the veterans we evaluated. No specific rheumatic diagnosis is characteristic of Gulf War veterans with unexplained illness referred to a rheumatology clinic. However, pain is common and widespread in these patients, and their health related quality of life is poor. Further research is necessary to determine the cause of the symptoms of veterans of the Gulf War.