Ten female and 2 male patients with chronic hepatitis C infection had fibromyalgia as a prominent musculoskeletal problem. In 9 patients, the fibromyalgia developed a mean of 13.4 years after the hepatitis C infection. In 2 patients, the 2 diseases occurred within weeks to a few months of each other, and in 1 patient, preexisting fibromyalgia was apparently aggravated by the hepatitis C infection. All patients had a possible blood or body fluid exposure event or high risk activity: intravenous blood products in 3, occupational needle stick in 1, tattoos in 3, intravenous drug use in 3 and promiscuous sexual practices in 2. Transaminases were moderately elevated in 10 patients, and chronic active hepatitis was found in 4 patients who were biopsied. All patients had prominent fatigue. Additional features not commonly seen in fibromyalgia patients included fluctuating synovitis in 5 patients, biopsy-proven leukocytoclastic vasculitis in 5, sicca symptoms in 3, Raynaud's phenomenon in 3, and cryoglobulinemia in 2. One patient died in multi-organ failure after treatment for systemic vasculitis. Rheumatologists and internists should be aware that patients with hepatitis C infection can have fibromyalgia that occurs concomitantly with other extrahepatic manifestations of hepatitis C.