The effects of acceptance versus suppression of emotion were examined in 60 patients with panic disorder. Prior to undergoing a 15-minute 5.5% carbon dioxide challenge, participants were randomly assigned to 1 of 3 conditions: a 10-minute audiotape describing 1 of 2 emotion-regulation strategies (acceptance or suppression) or a neutral narrative (control group). The acceptance group was significantly less anxious and less avoidant than the suppression or control groups in terms of subjective anxiety and willingness to participate in a second challenge, but not in terms of self-report panic symptoms or physiological measures. No differences were found between suppression and control groups on any measures. Use of suppression was related to more subjective anxiety during the challenge, and use of acceptance was related to more willingness to participate in a second challenge. The results suggest that acceptance may be a useful intervention for reducing subjective anxiety and avoidance in patients with panic disorder.