Intermittent explosive disorder (IED) is a psychiatric diagnosis applied to individuals who repeatedly engage in the acts of impulsive aggression. The IED-integrated research (IR) criteria clearly operationalize the severity and frequency of aggressive behavior required for the diagnosis. The IED-IR criteria allow subjects with borderline and/or antisocial personality disorder (BPD/AsPD) to receive a comorbid IED diagnosis. Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria for AsPD and BPD include anger and aggression. Aggressive outbursts in IED have a rapid onset, often without a recognizable prodromal period. High level of hostility and aggression negatively impact the quality of life across several dimensions, including interpersonal relationships, sleep quality, job satisfaction, and health. Completed analysis of a double-blind, placebo-controlled trial of fluoxetine on impulsive aggressive behavior in 100 subjects with IED demonstrates clear anti-aggressive efficacy for fluoxetine versus placebo.