Eligibility Criteria:
Inclusion Criteria:
* diagnosis of first episode of schizophrenia according to Diagnostic and Statistical Manual of Mental Disorders- Fourth Edition (DSM-IV) criteria and no history of neuroleptic medication
* Females and/or males aged 18 to 65 years
* Mild to moderate schizophrenia
Exclusion Criteria:
* Neuroleptic treatment prior to study enrollment
* Pregnancy or lactation
* Any DSM-IV Axis I disorder not defined in the inclusion criteria
* 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 enrolment 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 enrolment including but not limited to: phenytoin, carbamazepine, barbiturates, rifampin, St. John's Wort, and glucocorticoids
* Any history of neuroleptic treatment
* 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. angina pectoris, hypertension, congestive heart failure) as judged by the investigator
* Involvement in the planning and conduct of the study
* History of or evidence of significant brain malformation or neoplasm, head injury, cerebral vascular events, neurodegenerative disorder affecting the brain or prior brain surgery
* Concomitant treatment with psychotropic drugs (e.g. antidepressive agents, anticonvulsants, other neuroleptics) except benzodiazepines or hypnotics