In an epidemiological survey of females aged 20-49 years in Arendal, Norway, a prevalence of fibromyalgia according to the ACR criteria of 1990 of 10.5% was found. Thirty-four out of 40 women with fibromyalgia (85.0%) had, prior to the present population study, consulted a physician because of widespread pain and/or stiffness. Of these 34 women, 14 cases (41.2%) had been given a diagnosis of fibromyalgia. It is concluded that fibromyalgia represents one of the major causes of pain in the locomotor system, and unfortunately, the condition often remains undiagnosed for long periods.