This is a randomized, double-blind study to determine how well intramuscular (IM) olanzapine depot works compared to oral olanzapine; evaluate the safety and tolerability of IM olanzapine depot compared to oral olanzapine; evaluate different doses of IM olanzapine depot; and determine the blood levels of IM olanzapine depot in patients at different points in time after an injection.
Inclusion Criteria: * Patients must have schizophrenia * Patients must be clinically stable on antipsychotic medication * Patients must be retrospectively judged by investigators, based on clinical interview and impression, to have been stable (with respect to their symptoms of schizophrenia) for at least 4 weeks entry into the study * Patients must be an outpatient and have BPRS positive items scores of 4 or less to enter the study * Female patients of childbearing potential must be using a medically accepted means of contraception. Exclusion Criteria: * Patients must not have participated in a clinical trial of another investigational drug, including olanzapine, within 1 month (30 days) prior to study entry. * Female patients must not be pregnant or breast-feeding * Patients must not be experiencing acute, serious, or unstable medical conditions other than schizophrenia * Patients must not require concomitant treatment with any other medication with primarily central nervous system activity, including antidepressants, mood stabilizers, and anticonvulsants. * Patients must not have a substance (except nicotine or caffeine) dependence within the past 30 days