An Inpatient Study of the Effectiveness and Safety of Depakote ER in the Treatment of Mania/Bipolar Disorder

INCLUSION CRITERIA * Current primary diagnosis of bipolar I disorder, mania or mixed type * Acute exacerbation of mania associated with bipolar disorder as defined by Mania Rating Scale score \>= 18 * Hospitalized no more than 7 days at time of Screening or in process of being admitted * History of at least one prior manic or mixed episode within past 3 years, exclusive of the current episode. Prior manic or mixed episode must be separated from current episode by at least 2 months of sustained improvement EXCLUSION CRITERIA * History of schizophrenia or schizoaffective disorder * Axis I (e.g., anxiety disorder), or Axis II (e.g., personality disorder) that would interfere with compliance or confound interpretation of study results * Current manic or mixed episode is drug-induced or secondary to a medical disorder (e.g., AIDS, corticosteroids) * Current manic or mixed episode is believed to be caused by antidepressant use (i.e., antidepressant-induced mania) * Had first manic episode after age 60 * Has ever taken clozapine * Has received depot neuroleptic medication within one inter-injection interval of first dose of study drug * Urine toxicology screen is positive for phencyclidine (PCP), opiates, cocaine or amphetamines * History of active alcohol or substance dependence within past 3 months. * History of failed treatment on adequate valproate therapy for bipolar disorder * Has taken Depakote (DR or ER) regularly over the last 30 days * Has serious violent, homicidal, or suicidal ideation