PURPOSE: Because second generation antipsychotics (SGA) might affect the risk of suicide, systematic assessment of suicide risk associated with SGA in the postmarketing setting is important and of interest to regulatory authorities. To fulfill a postmarketing request, our objective was to determine suicide event (attempted or completed) incidence in patients with schizophrenia or bipolar disorder, prescribed aripiprazole. METHODS: Using administrative data from three US sources, we assessed study endpoints of suicide attempts and death by suicide in patients aged >/=18 enrolled continuously for >/=3 months in their health plans before receiving their first ever antipsychotic (November 2002-December 2005). RESULTS: Among 20 489 antipsychotic users (8985 patient-years), unadjusted suicide event rates (per 1000 patient-years) were: 20.69 (aripiprazole); 23.99 (olanzapine); 32.33 (quetiapine); 19.69 (risperidone); 48.52 (ziprasidone). Compared with current users of other SGA combined, aripiprazole users did not have an increased risk of suicide events (crude hazard ratio (HR) = 0.79, 95%CI: 0.48-1.30; adjusted HR = 0.69, 95%CI: 0.42-1.14-(controlling for study site, age, sex, index prescription year, antipsychotic use history, other pharmacotherapy exposure, comorbidity presence, schizophrenia/bipolar disorder, suicide attempts, number inpatient/outpatient encounters). CONCLUSIONS: In this large, multi-site study, compared with other SGA combined, aripiprazole is not associated with an increased risk of suicide events in an inception cohort of patients with ICD-9/ICD-10 codes indicative of schizophrenia or bipolar disorder.