OBJECTIVES: To assess recent pharmacologic treatment patterns for hospitalized bipolar patients. METHODS: Using Premier's PerspectiveTM database, the largest U.S. hospital drug utilization database, hospitalized bipolar patients discharged between January 1999 and September 2001 were identified. Psychotropic treatment patterns and their relationship with diagnoses, illness severity, and patient and institution characteristics were analyzed. RESULTS: Of 36,339 patients (61% female, mean age 39.7 years), 28.9% were depressed, 21.6% manic, 21.0% mixed, and 28.5% other episodes. Valproate (45.9%) and olanzapine (30.2%) were most commonly prescribed (Lithium, 24.9%). On average, patients received 3.87 psychotropics; 77.1% received 3 and 32.5% received 5. Only 7.2% received monotherapy. Antipsychotic + mood stabilizer combinations were used by 58.0%. Mood stabilizers or antipsychotics alone combined with other classes were used by 23.1% and 12.6% of patients, respectively. Among depressed patients, 79.1% used antidepressants versus 25.5% of manic patients. In depressed patients with psychosis, 74.5% received atypicals versus 42.8% of patients without psychosis. However, 61.5% of depressed patients received anxiolytics and 24.5% received hypnotics. Olanzapine use increased, and risperidone, valproate, and lithium use decreased from 1999-2001. Female, greater severity, and depressed/mixed diagnosis increased pharmacotherapy complexity. CONCLUSIONS: Pharmacotherapy for hospitalized bipolar patients is complex. Combinations of 3 psychotropics were dominant treatment regimens.