OBJECTIVE: To examine the effects of long-term treatment with citalopram or clomipramine on subjective phobic symptoms in patients with panic disorder. DESIGN: Double-blind, parallel-group, five-arm study. PATIENTS: Patients aged 18 to 65 years with panic disorder (DMS-III-R diagnosis) and with no major depressive symptoms. INTERVENTIONS: Four hundred and seventy-five patients were randomized to 8 weeks of treatment with either citalopram (10 to 15 mg per day; 20 to 30 mg per day; or 40 to 60 mg per day), clomipramine (60 to 90 mg per day) or placebo. Two hundred and seventy-nine patients continued treatment after the 8-week acute phase. OUTCOME MEASURES: Phobic symptoms were assessed using the Phobia Scale and the Symptom Checklist's (SCL-90) phobia-related factors. RESULTS: At all dosages, citalopram was more efficacious than placebo, with 20 to 30 mg generally being the most effective dosage. Citalopram (20 to 30 mg) generally decreased phobic symptoms significantly more than placebo after Month 3. Interpersonal sensitivity decreased when measured on the respective SCL-90 sub-scale. Alleviation of phobic symptoms generally continued to increase towards the end of the treatment. The effect of clomipramine was not as consistent. CONCLUSIONS: All active treatment groups, especially the group receiving 20 to 30 mg per day of citalopram, effectively controlled phobic symptoms in patients with panic disorder. Long-term treatment with citalopram further decreased phobic symptoms.