To determine if long-term treatment, up to 6 months, with Depakote ER is safe and effective in the treatment of bipolar I disorder in children and adolescents.

Inclusion Criteria:

• Subject and subject's legal representative have voluntarily signed and dated an IRB-approved informed assent form and an IRB-approved informed consent form, respectively, before any study-specific procedures or tests are performed.
• The subject was randomized into Study M01-342 and either completed the study or prematurely discontinued due to ineffectiveness.
• The subject is male or a non-pregnant, non-lactating female.
• Subject is judged to be in general good health based upon the results of a physical examination, vital signs, 12-lead electrocardiogram (ECG), and laboratory profile (as described in Section 5.3.1)

Exclusion Criteria

• Subject is female, of childbearing potential, and not using an effective method of birth control (e.g., total sexual abstinence or contraceptives).
• Subject experienced a serious adverse event in Study M01-342, which the investigator considered "possibly" or "probably related" to study drug.
• Subject is violent, homicidal, or suicidal such that, in the opinion of the investigator, the subject is at significant imminent risk of hurting self or others.
• Subject has any of the following abnormal laboratory results at the last assessment prior to Day 1: Platelet count </= 100,000/µL; ALT or AST >/= 2 times Upper Limit of Normal (ULN)
• The subject is taking a protocol allowed medication for ADHD that has not been stable for at least 3 months prior to Day 1, is expected to require a dosage adjustment during the study, or that, in the investigators opinion, may be exacerbating mood symptoms.
• Subject requires treatment with or has taken a protocol-prohibited medication (see Appendix D) within 5 elimination half lives of Day 1.
• Subject has received an investigational drug, other than Depakote ER in Study M01-342, within 30 days prior to Day 1 of this study.
• In the investigator's opinion, long-term treatment with Depakote ER for the subject's mania associated with bipolar disorder is contraindicated.
• For any reason, subject is considered by the investigator to be an unsuitable candidate for this study.