OBJECTIVES: To investigate the incremental health care resource use and costs associated with Fibromyalgia diagnosis. METHODS: We used data from the UK General Practice Research Database (GPRD) to study the health care resource use of patients prior to and following their FM diagnosis. All patients in GPRD with a diagnosis of Fibromyalgia from January, 1 1998 and 2-years minimum of data prior to their first diagnosis, were included. Incidence rates of the clinical, therapy, referral, test and consultation events of interest were estimated for up to 10-years prior to and up to 4-years after the date of the diagnosis. A simple cost assessment was performed to compare the cost of diagnosed patients with Fibromyalgia and the predicted costs (based on trend analysis) of those patients if they wouldn't have been diagnosed. RESULTS: There were 2260 diagnoses of Fibromyalgia. Of these, 81.3% were in females and mean age was 49-years old. Following the diagnosis of Fibromyalgia, the visits rate related to depression stabilised and then declined to 13 per 100person-years by 4-years post-diagnosis. Referral rates declined considerably and the incidence of tests appeared to stabilise. Rheumatology referrals dropped to near control levels by 4 years following the Fibromyalgia diagnosis. In total, it was estimated that £9,082 per 100patient-years were saved by making the diagnosis. The major contributor to this savings was the reduced level of “other referrals” (£5,599), followed by rheumatologists (£1,880), GP consultations (£871) and tests (£621) The reduction in drugs contributed less (£112 per 100 person-years). CONCLUSION: Fibromyalgia is associated with considerable, long-term morbidity and healthcare resource use. A definitive diagnosis of Fibromyalgia is associated with a temporary increase in the use of TCAs and SSRIs and with a reduction in consultations and referrals for associated symptoms and in the healthcare resources and costs used to manage affected patients.