Seroquel Switching Study: Feasibility of Switching Any Antipsychotic Treatment to Seroquel in Patients With Schizophrenia

Inclusion Criteria: * Patients who in their own and/or in the Investigator's opinion, consider ongoing antipsychotic treatment inadequate, because of insufficient efficacy and/or tolerability. * Female patients of childbearing potential must have a negative serum pregnancy test at enrolment and be willing to use a reliable method of birth control, ie, barrier method, oral contraceptive, implant, dermal contraception, long-term injectable contraceptive, intrauterine device, or tubal ligation during the study. * Able to understand and comply with the requirements of the study, as judged by the Investigator. Exclusion Criteria: * Meeting the criteria for any other (than schizophrenia) Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) Axis I diagnosis, concomitant organic mental disorder or mental retardation. * Substance abuse or dependence as defined by DSM-IV and not in full remission. A urine drug screen test will be performed. The Investigator will evaluate the results along with medical history to determine if the patient meets DSM-IV criteria for substance abuse or dependence. * Risk of transmitting human immunodeficiency virus (HIV) or hepatitis B, via blood or other body fluids, as judged by the Investigator. * Patients who, in the opinion of the Investigator, pose an imminent risk of suicide or a danger to self or others.