OBJECTIVE: Prescribing patterns in bipolar disorder are complex and varied. The objective of this analysis was to identify how various patterns of treatment relate to direct costs. METHODS: The PharMetrics Integrated Outcomes Database of adjudicated medical and pharmaceutical claims for over 3 million patients from 11 U.S. health plans was utilized. 3,648 bipolar patients were identified based on the following criteria: two claims with ICD-9-CM diagnosis for bipolar disorder (296.0, 296.1, 296.4-296.8) that were not accompanied by a unipolar depression claim on the same day, age between 10 and 64, and 1 year of continuous eligibility prior to and following the initial bipolar diagnosis. Thirteen months of data were analyzed (1 month pre diagnosis, 12 months post diagnosis). RESULTS: Eighty-two percent of patients (2992) were treated with medication. For drug treated patients, on average, the total cost over the 13-month period is $12,416 per patient. Of this amount, 65% of the costs ($8018) are bipolar-related; with a 5:1 ratio of medical services related costs ($6,691) to medication costs ($1327). Patients initiating on poly-pharmacy incur higher total bipolar costs ($10,137) than their cohorts who initiated on mono therapy ($6,683). As expected, as the number of drugs used increases, total bipolar costs steadily rise with the average being $3,883 for one drug, $11,419 for four drugs and $19,040 for 9 drugs. Additionally, as the number of treatment regimes per patient increases, so do costs. Total bipolar costs for patients having only one treatment regime average $3,528, whereas patients experiencing 3 switches (four regimes) average $12,553. CONCLUSION: Many factors are related to the cost of treating bipolar patients. Further investigation needs to be conducted in order to understand which of these factors might be cost containment opportunities.