Inclusion Criteria:

• Provision of written informed consent
• A diagnosis of fibromyalgia according to the following American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia
• History of widespread pain has been present for at least three months (defined as: Pain in both sides of the body; Pain above and below the waist with additional, axial skeletal pain must be present. Low back pain is considered lower segment pain)
• Pain in 11 of 18 tender point sites on digital palpation
• Females and males from age 18 to age 60 inclusive
• Female patients of childbearing potential must be using a reliable method of contraception and have a negative urine human chorionic gonadotropin (HCG) test at enrollment
• Able to understand and comply with the requirements of the study
• Unsatisfactory response to previous treatment as indicated by a score equal to or greater than 4 on the FIQ

Exclusion Criteria:

• Pregnancy or lactation
• Patients who, in the opinion of the investigator, pose an imminent risk of suicide or a danger to self or others
• Known intolerance or lack of response to quetiapine fumarate, as judged by the investigator
• Use of any of the following cytochrome P450 3A4 inhibitors in the 14 days preceding enrollment including but not limited to: ketoconazole, itraconazole, fluconazole, erythromycin, clarithromycin, troleandomycin, indinavir, nelfinavir, ritonavir, fluvoxamine and saquinavir
• Use of any of the following cytochrome P450 inducers in the 14 days preceding enrollment including but not limited to: phenytoin, carbamazepine, barbiturates, rifampin, St. John's Wort, and glucocorticoids
• Administration of a depot antipsychotic injection within one dosing interval (for the depot) before randomisation
• Substance or alcohol dependence at enrollment (except dependence in full remission, and except for caffeine or nicotine dependence), as defined by DSM-IV criteria
• Opiates, amphetamine, barbiturate, cocaine, cannabis, or hallucinogen abuse by DSM-IV criteria within 4 weeks prior to enrollment
• Medical conditions that would affect absorption, distribution, metabolism, or excretion of study treatment
• Unstable or inadequately treated medical illness (e.g. diabetes, angina pectoris, hypertension) as judged by the investigator
• Involvement in the planning and conduct of the study
• Previous enrollment or randomization of treatment in the present study
• Participation in another drug trial within 4 weeks prior enrollment into this study or longer in accordance with local requirements

• A patient with Diabetes Mellitus (DM) fulfilling one of the following criteria:

  • Unstable DM defined as enrollment glycosylated hemoglobin (HbA1c) >8.5%
  • Admitted to hospital for treatment of DM or DM related illness in past 12 weeks.
  • Not under physician care for DM
  • Physician responsible for patient's DM care has not indicated that patient's DM is controlled.
  • Physician responsible for patient's DM care has not approved patient's participation in the study
  • Has not been on the same dose of oral hypoglycaemic drug(s) and/or diet for the 4 weeks prior to randomization. For thiazolidinediones (glitazones) this period should not be less than 8 Weeks.
  • Taking insulin whose daily dose on one occasion in the past 4 weeks has been more than 10% above or below their mean dose in the preceding 4 weeks
• An absolute neutrophil count (ANC) of less than or equal to 1.5 x 10^9 per liter
• dementia

• Patients identified as meeting criteria for the Metabolic Syndrome, defined by meeting any 3 of the following:

  • Waist circumference greater than 40 inches (men) or 35 inches (women)
  • Triglycerides greater than 150 mg/dl
  • HDL cholesterol less than 40 mg/dl (men) or 50 mg/dl (women)
  • High blood pressure greater than 130/ greater than 85
  • Fasting glucose greater than 110 mg/dl