OBJECTIVE: Several classes of medications have demonstrated efficacy in panic disorder, but direct comparison of 2 proven treatments is still uncommon. The purpose of this study was to compare sertraline and paroxetine in the acute treatment of panic disorder. METHOD: Adult outpatients with panic disorder with or without agoraphobia (DSM-IV and ICD-10 criteria) were randomly assigned in double-blind fashion to 12 weeks of treatment with flexible doses of sertraline (titrated up to 50-150 mg/day; N = 112) or paroxetine (titrated up to 40-60 mg/day; N = 113). Patients were then tapered off medication over 3 weeks. The primary analysis was a noninferiority analysis of Panic and Agoraphobia Scale (PAS) scores. Secondary measures included panic attack frequency and the Clinical Global Impressions-Improvement scale (CGI-I) (with responders defined as those with a CGI-I score or = 7% weight gain (7% vs.