• The primary efficacy measure will be the time to relapse. Relapse will determined by; need for additional pharmacotherapy, hospitalization for an affective episode, increase of >/= 50% in HAM-D and YMRS scores. [ Time Frame: Patients will be seen weekly during preliminary phase and biweekly during the open label phase ] [ Designated as safety issue: Yes ]
  

• The differences in the frequency of affective episodes in the 6-month prior to the treatment with ERC-CBZ and 6 months after treatment initiation will also be measured. Secondary efficacy measures will include; changes in the 17- Item Hamilton Depression [ Time Frame: Patients will be seen weekly during the preliminary phase and biweekly during the open label phase ] [ Designated as safety issue: No ]
  

Inclusion Criteria:

1. Subjects, 19 years and older with DSM-IV defined Bipolar Disorder with a history of the rapid cycling within the past 12 months.
2. Subjects may be either in a manic, mixed or depressive phase at time of study entry.
3. Subjects must be on lithium therapy for 6 months or longer. Stable lithium therapy will be defined as: No changes in lithium dosage for at least 2 weeks prior to study entry and a therapeutic lithium level (0.6 to 1.2 mEq) prior to study entry.

Exclusion Criteria:

1. Subjects with a lifetime history of Schizophrenia or Schizoaffective Disorder
2. If patients are on thyroid replacement therapy they have to on stable doses for the past 3 months at study enrollment.
3. Presence of active suicide ideations or score of > 3 on the suicide subscale of the 17 - item HAM-D.
4. Current substance dependence (excluding nicotine) defined as no dependence criteria for 30 days prior to study enrollment
5. Subjects with a history of non-response to carbamazepine or lithium
6. Subjects who are pregnant or planning to become pregnant
7. Subjects with a history of allergic/idiosyncratic reaction or intolerability to carbamazepine or lithium.