It is important to recognize the diagnosis of fibromyalgia (FM) to adequately advise patients with this chronic pain disease. FM coexists with other rheumatic diseases and may therefore serve as a confounder in connection with estimation of disease activity. The aetiology and pathogenesis of FM remain unknown, although central sensitisation seems to play a major role. Following exclusion of a number of differential diagnoses, the remaining patients have several treatment options including centrally-acting medication.