The purpose of this study is to characterize olanzapine pharmacokinetics: the inter- and intra- subject variabilities of olanzapine pharmacokinetics; and the potential influence of patient factors such as age, weight, gender, origin, and smoking status on olanzapine pharmacokinetics in adolescents with schizophrenia or bipolar I disorder. This study will also assess the safety of olanzapine delivered orally.

Inclusion Criteria:

• Male or female patients, 13 through 17 years of age (must not have reached their 18th birthday prior to Visit 1).
• Female patients must not be pregnant or nursing.
• Patient and patient's parent/authorized legal representative must have a level of understanding sufficient to perform all tests and examinations required by the protocol, and must have given informed consent.
• Patient must have a previously documented diagnosis of schizophrenia or bipolar I according to the DSM-IV-TR, and either confirmed previously by K-SADS-PL or be confirmed by K-SADS-PL at Visit 1.

Exclusion Criteria:

• Patients must not be experiencing acute, serious, or unstable medical conditions other than schizophrenia or bipolar I disorder.
• Patients are not allowed into the study if they currently meet the criteria for the depressed phase of bipolar disorder or are diagnosed with Bipolar II Disorder.