• Assess the efficacy of a flexible dose of olanzapine compared with placebo in the treatment of mania in bipolar I disorder (manic or mixed episode associated with bipolar I disorder, with or without psychotic features) in adolescents
  

• Assess additional efficacy as measured by Y-MRS,CGI-BP Severity of Illness, CGI-BP Severity of Illness (CGI-BP Severity of Mania, CGI-BP Severity of Depression, and CGI-BP Severity Overall)
  
• Assess additional efficacy as measured by Children’s Depression Rating Scale-Revised (CDRS- R);Attention-Deficit/Hyperactivity Disorder Rating Scale-IV-Parent Version: Investigator Administered and Scored (ADHDRS-IVPI) and Overt Aggression Scale (OAS).
  
• Assess the safety of olanzapine and quality of life associated with olanzapine compared with placebo.
  
• Compare the frequency of response of up to 3-weeks, double-blind treatment and up to an additional 26 weeks of open-label olanzapine treatment
  

Inclusion Criteria:

• Male or female patients, 13 to 17 years of age who must not yet have reached their 18th birthday prior to Visit 1, when informed consent is obtained.
• Patients must have a diagnosis of bipolar I disorder and currently display an acute mania or mixed episode.
• Both the patient and the patient's parent/authorized legal representative must understand the nature of the study and must sign a document granting consent.
• Female patients of child-bearing potential must test negative for pregnancy at the time of enrollment based on a serum pregnancy test.

Exclusion Criteria:

• Female patients who are either pregnant or nursing.
• Current diagnosis of schizophrenia, schizophreniform disorder, or schizoaffective disorder.
• Patient with acute or unstable medical conditions, such that intensive care unit hospitalization for the disease is anticipated within 6 months.
• Patients who have previously not responded to an adequate dose and/or duration of olanzapine treatment.
• Patients who have been judged clinically to be serious suicidal risks.