The purposes of this study are to assess the efficacy, safety, and side effects among doses approved by the Food and Drug Administration and higher (not FDA approved) doses of olanzapine in patients with schizophrenia or schizoaffective disorder.

Inclusion Criteria:

• You must be 18 to 60 years old
• You must have been diagnosed with schizophrenia or schizoaffective disorder
• You must be able to visit the doctor's office 8 times over a 9 week period
• You must agree to participate with all tests and examinations that are required for this study

Exclusion Criteria:

• You are a woman and are pregnant or breastfeeding
• You presently have an acute or unstable medical illness
• You have a history of an allergic reaction to olanzapine
• You are taking medications that are not permitted in this study. Your physician will discuss these with you
• You have taken part in another clinical research trial within the last 30 days or you have received treatment with a drug in the last 30 days that has not received regulatory approval.