Objective: To compare time to all-cause discontinuation (TTAD) across alternative antipsychotics in the treatment of bipolar disorder (BD). Methods: Data from a commercial health plan from July 1, 2003 to June 30, 2006 were used to identify non-institutionalized patients with bipolar disorder (ICD-9 296.4-296.8) but no history of schizophrenia (ICD-9 295.xx). Patients initiating treatment using a typical antipsychotic (TAP), atypical antipsychotic (AAP: aripiprazole, olanzapine, quetiapine, risperidone or ziprasidone), mood stabilizer or antidepressant were included. Episodes were divided into three categories: restarting treatment after a break in drug therapy >15 days with the drug used in the previous episode, switching therapy with or without a break in treatment, and augmentation therapy. First observed episodes were excluded from the analysis due to uncertainty concerning the patient's prior treatment history. A total of 106,447 episodes were included in the analyses using ordinary least squares (OLS) regression models of TTAD adjusting for age, gender, geographic region, drug use history, prior medical care use, bipolar disorder diagnosis and co-morbid medical conditions. Results: Augmentation constituted over half of all treatment episodes (55.3%) and only 20% of all episodes included an antipsychotic. Patients initiating augmentation episodes achieved significantly longer TTAD initial therapy than patients initiating restart (+80 days, p<0.0001) or switching episodes (+13 days, p<0.0001). Moreover, these estimated differences increased significantly when TTAD was measured over all BD-related therapies (+155 days and +284 respectively). OLS results comparing initial therapies favored quetiapine, ziprasidone and aripiprazole relative to TAP in restart (+15 to +36 days), switching (+18 to +25 days) and augmentation episodes (+28 to +48 days)(p<0.05 for 7 of 9 estimates). Conclusion: In a commercially-insured population, patients with bipolar disorders initiating therapy using ziprasidone, aripiprazole or quetiapine have longer TTAD that TAP patients. Patients initiating augmentation therapy have much longer TTAD than other patients, especially when measured across all psychotropic medications.