Seventy-five outpatients with moderate to severe panic disorder were randomly assigned to receive 8 weeks of fluvoxamine, cognitive therapy, or placebo. Fifty-five patients completed the treatment protocol. Fluvoxamine was found to be an effective and well-tolerated treatment for panic using clinician- and patient-rated variables. Subjects receiving cognitive therapy also showed improvement, but this improvement did not significantly differ from the experience of the placebo-treated group for most comparisons. Fluvoxamine was superior to cognitive therapy for many ratings, but cognitive therapy was not superior to fluvoxamine on any rating. Fluvoxamine also produced improvement earlier than cognitive therapy. At the main comparison point (week 4), 57% (13/23) of patients receiving fluvoxamine were rated moderately improved or better vs 40% (8/20) of the group given cognitive therapy and 22% (5/23) of the placebo-treated group. At that point, 43% (10/23) of the fluvoxamine recipients vs 25% (5/20) of cognitive therapy and 4% (1/23) of placebo recipients were free of panic attacks.