OBJECTIVE: Hospitalization and inpatient charge comparisons for bipolar and manic patients receiving atypical and conventional antipsychotics. METHODS: Analysis of a claims database (1999-2003) representing 50 million US insured patients identified 12,835 treatment episodes of monotherapy for bipolar and manic disorders with atypicals (risperidone, olanzapine, quetiapine, ziprasidone) and conventionals (haloperidol, perphenazine, thioridazine, thiothixene). Hazard ratios (HR) for hospitalization risks were estimated with Cox regression adjusting for patient characteristics. Inpatient charges were based on these estimates and estimated hospital stays. RESULTS: Risperidone and olanzapine had significantly (P<0.05) higher risks of hospitalization than quetiapine (HR 1.185 and 1.187, respectively) and trended (P<0.10) toward higher risks than ziprasidone (HR 1.443 and 1.447, respectively), translating into higher inpatient charges of $194-$389 per patient per year. On comparing the atypicals in manic rapid cyclers (a high hospitalization subgroup), risperidone had a significantly (P<0.05) higher risk of hospitalization than olanzapine (HR=3.309) and olanzapine trended (P<0.10) toward longer stays than quetiapine (7.56 days longer), both translating into higher inpatient charges. CONCLUSION: In treating bipolar and manic disorders, risperidone and olanzapine may have higher risks of hospitalization than quetiapine. In treating manic rapid cyclers, olanzapine may have a lower risk of hospitalization than risperidone, but longer stays than quetiapine.