Rigorously designed clinical trials have demonstrated the efficacy and safety of fluoxetine in adults with major depressive disorder and obsessive-compulsive disorder (OCD) but not in patients below 18 years old. This report describes a randomized, double-blind, placebo-controlled, fixed-dose (20 mg qd) trial of fluoxetine in 14 children and adolescents with OCD, ages 8 to 15 years old; the study was 20 weeks long with crossover at 8 weeks. Obsessive-compulsive symptom severity was measured on the Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS) and the Clinician's Global Impression-Obsessive Compulsive Disorder scale (CGI-OCD). The CY-BOCS total score decreased 44% (N = 7, p = .003) after the initial 8 weeks of fluoxetine treatment, compared with a 27% decrease (N = 6, p = .13) after placebo. During the initial 8 weeks, the magnitude of improvement for the fluoxetine group significantly exceeded that for the placebo group as measured by the CGI-OCD (p = .01) but not by the CY-BOCS (p = .17). The most common drug side effects were generally well tolerated. The results suggest that fluoxetine is a generally safe and effective short-term treatment for children with OCD.