Effectiveness of Ziprasidone for Patients With Schizophrenia

Inclusion Criteria: * Male and female aged 18-55 years treated with risperidone, olanzapine, amisulpride, quetiapine and typical antipsychotics. * Both in- and outpatients who met Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for schizophrenia or schizoaffective disorder. * Their primary psychiatric clinician determined that they would benefit from a change in their medications, either because of suboptimal efficacy or because of side effects. Exclusion Criteria: * Those who are treated with medications that prolong the QTc interval. * Those who have any other axis I DSM-IV diagnoses. * Those who have a history of substance abuse or dependence within 1 month. * Those who have clinically significant abnormal laboratory values or any other abnormal baseline laboratory findings considered by psychiatrists to be indicative of conditions that might affect the study results. * Those who have a past history of hypersensitivity or intolerance to ziprasidone. * Those who have history of clozapine use within 1 month. * Those who participated in clinical trials within 1 month before entering the study entry. * Those who have used depot antipsychotics within one cycle before entering the study. * Those who are pregnant or are breast feeding. * Those who have a immediate risk of harming self or others or history of suicide attempts in the year before the screening precluded inclusion in the study. * The patients unable/unlikely to comprehend/follow the protocol.