ABSTRACT: Aripiprazole modulates dopaminergic and serotonergic pathways that may play a role in the pathogenesis of Tourette's disorder (TD). This trial evaluated the efficacy and safety of oral aripiprazole in the suppression of tics in children and adolescents with TD.This phase 3, randomized, double-blind, placebo-controlled trial ( ClinicalTrials.gov , NCT01727700) recruited patients who were 7-17 years old with a diagnosis of TD from hospitals, private practices, and research clinics at 76 sites in the United States, Canada, Hungary, and Italy. Patients were randomized in a 1:1:1 ratio by using an interactive voice/web-response system to low-dose aripiprazole (5?mg/day if <50?kg; 10?mg/day if ?50?kg), high-dose aripiprazole (10?mg/day if <50?kg; 20?mg/day if ?50?kg), or placebo for 8 weeks. Randomization was stratified by region (North America or Europe) and baseline body weight (<50?kg vs. ?50?kg). The primary efficacy endpoint was mean change from baseline to week 8 in the Yale Global Tic Severity Scale Total Tic Score (YGTSS-TTS) for the intent-to-treat population.Between November 2012 and May 2013, 133 patients were recruited and randomized to low-dose aripiprazole (n?=?44), high-dose aripiprazole (n?=?45), or placebo (n?=?44). Least-squares mean treatment differences versus placebo in change from baseline to week 8 in the YGTSS-TTS were statistically significant (high dose, -9.9 [95% confidence interval, CI, -13.8 to -5.9], low dose, -6.3 [95% CI, -10.2 to -2.3]). At week 8, 69% (29/42) of patients in the low-dose and 74% (26/35) of patients in the high-dose aripiprazole groups demonstrated a Clinical Global Impression-Tourette's Syndrome improvement score of 1 (very much improved) or 2 (much improved) compared with 38% (16/42) in the placebo group. The most common adverse events (AEs) were sedation (low dose, 8/44 [18.2%], high dose, 4/45 [8.9%], placebo, 1/44 [2.3%]), somnolence (low dose, 5/44 [11.4%], high dose, 7/45 [15.6%], placebo, 1/44 [2.3%]), and fatigue (low dose, 3/44 [6.8%], high dose, 7/45 [15.6%], placebo, 0). No serious AEs or deaths occurred.This study indicates that oral aripiprazole is a safe and effective treatment for tics in children and adolescents with TD.