Chronic exercise has been shown to have therapeutic effects in panic disorder (PD). The mechanism of these effects is unknown. Acute exercise reduces the effect of a panic challenge in healthy volunteers. Such an effect has not yet been demonstrated in PD patients. The present study aimed at exploring the antipanic effects of acute exercise on a 35%CO2 panic provocation in treatment-naïve PD patients to further elucidate the mechanisms of the beneficial effects of exercise on panic.