The pathophysiology of fibromyalgia remains unknown. Several reports have recently suggested the novel concept that fibromyalgia is due to the central nervous system becoming hyper-responsive to a peripheral stimulus. The effect of electroconvulsive therapy (ECT) as pain remedication in cases of fibromyalgia without major depressive disorder was studied in a prospective trial lasting three months. All of the patients taking part in the study fulfilled the American College of Rheumatology diagnostic criteria for fibromyalgia. Technetium-99m ethyl cysteinate dimer single photon emission computed tomography was used to assess regional cerebral blood flow (rCBF) before and after a course of ECT. Pain assessment in the patients was undertaken by use of the visual analog scale (VAS) and by evaluation of tender points (TPs). Beck's depression inventory (BDI) was further used to assess depressive mood change in the patients. Our study clearly demonstrated that pain was significantly less severe after ECT, as indicated by the VAS scale for pain and the evaluation of TPs. A further notable observation was that thalamic blood flow was also improved. We conclude that a course of ECT produced notable improvements in both intractable severe pain associated with fibromyalgia and also in terms of thalamic blood flow.