Eighty-seven patients with a DSM-III diagnosis of obsessive-compulsive disorder (OCD) without depression were entered into a double-blind, placebo-controlled study of the efficacy of sertraline, a new serotonin uptake inhibitor. After a 1-week washout period, patients were randomly assigned to receive either placebo or sertraline. After a 2-week titration period in which the once-daily sertraline dose was increased from 50 mg/day to a maximum of 200 mg/day, dosage was maintained until the end of the eighth week, then patients were titrated off medication over the next 2 weeks. Efficacy was measured by the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), NIMH General Obsessive-Compulsive Scale, Maudsley Obsessive Compulsive (MOC) Inventory, and Clinical Global Impressions (CGI) Severity and Improvement scales. Results on the MOC Inventory showed trends in favor of active drug that were not statistically significant compared with placebo. Results of the Y-BOCS total score, the NIMH score, and the global severity and improvement scores demonstrated a statistically significant superiority of sertraline compared with placebo.