OBJECTIVE To assess the efficacy and safety of paroxetine for the treatment of pediatric obsessive-compulsive disorder. METHODS Children (7-11 years of age) and adolescents (12-17 years of age) meeting DSM-IV criteria for obsessive-compulsive disorder were randomized to paroxetine (10-50 mg/day) or placebo for 10 weeks. The primary efficacy measure was change from baseline in the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS) total score at week 10 last observation carried forward end point. Safety was assessed primarily through adverse event monitoring. RESULTS A total of 207 patients were randomized to treatment. Of these, 203 were included in the intention-to-treat population. Adjusted mean changes from baseline at week 10 observation carried forward end point in CY-BOCS total score for patients receiving paroxetine and placebo were -8.78 (SE=0.82) and -5.34 points (SE=0.77), respectively. The adjusted mean difference, -3.45 in favor of paroxetine, was statistically significant (95% confidence interval=-5.60 to -1.29, p=.002). Adverse events were generally mild to moderate in intensity. A total of 10.2% (10/98) of patients in the paroxetine group and 2.9% (3 of 105) in the placebo group discontinued treatment because of adverse events. CONCLUSIONS Paroxetine is an effective and generally well-tolerated treatment for obsessive-compulsive disorder in children and adolescents.