To assess the efficacy of 24-week treatment with quetiapine in patients with schizophrenia or schizoaffective disorder

Inclusion Criteria:

• The patient and the patient's legal representative (if any) must understand the nature of the study and must have given written consent
• The patient suffers from schizophrenia or schizoaffective disorder according to DSM-IV-TR
• The patient is between 18 and 65 years old(extremes included)
• On the basis of physical and neurological examination, medical history, the patient is, in the investigator's opinion, otherwise healthy
• If the subject is a female of childbearing potential, she must be not pregnant or breast-feeding and be using a reliable method of contraception. Reliable methods may include abstinence, hormonal contraceptives (eg,oral contraceptives or long-term injectable or implantable hormonal contraceptives), double-barrier methods (eg, condom and diaphragm, condom and foam, condom and sponge), intrauterine devices, and tubal ligation

Exclusion Criteria:

• The patients who have known hypersensitivity to quetiapine