Background: High comorbidity between panic disorder with/without agoraphobia (PD/A) and irritable bowel syndrome (IBS) has been identified in the literature. These findings have resulted in the recent development of neurobiological models to explain their overlapping symptoms and related origins. This study was a preliminary investigation of the influence of cognitive behavioral therapy (CBT) for PD/A on PD/A patients with and without comorbid IBS. Methods: All patients completed a thorough intake assessment, brief waitlist period, and a 12-week CBT group for PD/A. Results: The results demonstrated significant reductions in the symptoms of anxiety, depression, and overall impairment in both patient groups (ts>2.3; Ps<.05). In addition, PD/A patients with comorbid IBS also experienced reductions in the disability and distress associated with their gastrointestinal symptoms of IBS (ts>1.9; Ps<.07). Conclusions: Although additional research still is needed, these preliminary findings suggest that CBT for PD/A can be used to simultaneously treat comorbid symptoms of PD/A and IBS. Implications for the neurobiological models for these comorbid conditions were discussed. Depression and Anxiety, 2011. © 2011 Wiley Periodicals, Inc.