OBJECTIVES: Fibromyalgia syndrome (FM) is an under diagnosed disorder of unknown etiology estimated between 0.5% and 5% in the general population. There is relatively little recent data on the epidemiology of FM world-wide, and specifically in Europe. The aim was to estimate the prevalence of Fibromyalgia Syndrome (FM) in clinical setting and in general population, in five European countries with the same methodology, METHODS: All patients addressed to the eight participating outpatient rheumatology clinics in a month were interviewed using the London Fibromyalgia Epidemiological Study Screening Questionnaire adding two questions on fatigue. The diagnosis of FM was confirmed using American College of Rheumatology classification criteria. The questionnaire was also administered by phone to a representative community sample more than 15 years old, selected by the quota method, in each country. The prevalence of FM was estimated in the general population, applying the predictive positive value in consultation, to the positive screens, RESULTS: A total of 46% of patients seen in rheumatology outpatients clinics were found positive for chronic widespread pain, 31.9% for widespread pain and fatigue. A total of 6.2% [15.9-16.4] were confirmed to be FM. In the general population, 13.3% were found positive for widespread pain and 6.7 % for widespread pain and fatigue. The FM prevalence in the general population, was 4.7% [4.0–5.3], when patients screened positive for chronic widespread pain were considered. If fatigue is added, the prevalence was 2.9% [2.4–3.4]. FM patients had a mean age of 54 years old (SD:12.5) and 94.1% of them where females. These last have a greater risk (5.2 [2.6-10.3]) of having FM. Likewise prevalence rises with age until 75-84 years, CONCLUSIONS: The FM prevalence, similar to that observed in Canada and United States, represents 6 million sufferers in the five European countries studied.