OBJECTIVES: The absence of objective signs and lack of tests make patient complaints fundamental to a presumptive diagnosis of fibromyalgia. To make diagnosis easier, H. Moldofsky has developed a questionnaire of 6 items related to diffuse pain, fatigue, psychological distress, unrestorative sleep and impaired well-being. To validate the FMQ (Fibromyalgia Moldofsky Questionnaire) as a tool to aid diagnosis, METHODS: A representative sample of 1500 subjects from the general UK population was constituted using the quota method. The FMQ questionnaire, was administered along with two validated questionnaires (LFESSQ London Fibromyalgia Epidemiology Study Screening Questionnaire and CES-D Center for Epidemiologic Studies Depression Scale) and a questionnaire assessing a decline in the restorative effects of sleep (SQA Sleep Quality Assessment). The maximum score of 18 reflected a strong presumption of fibromyalgia syndrome. Internal consistency, structural and clinical validity were tested. The sensitivity and specificity were also assessed, RESULTS: Internal consistency was satisfactory (αCronbach>0.7). The items composing each dimension were pertinent to the dimension that they represented (R>0.4) and were not correlated with any other dimension. Subjects responding positively on the LFESSQ had an FMQ score that was significantly higher than subjects who responded negatively (8.6 [7.9-9.3] vs 4.1 [3.9-4.3], p<0.001). Similar differences were observed between those subjects who had or did not have probable depressive symptoms (8.0 [7.4-8.6] vs 4.0 [3.8-4.2], p<0.001) and between subjects experiencing a decline in the restorative effect of sleep or not (7.3 [7.0-7.6] vs 3.5 [3.3-3.7], p<0.001).The FMQ had a sensitivity of 46 to 54%, depending on the specific dimension and questionnaire studied. Specificity was optimal (90 to 95%), CONCLUSIONS:The results observed during this psychometric validation showed that the FMQ questionnaire responded to the objectives that we had established and therefore allows referring physicians to send subjects with presumed fibromyalgia to specialist investigation centres.