Cognitive behavioral treatment (CBT) protocols for panic disorder (PD) typically include some form of interoceptive exposure (IE)--repeated exposure to internal sensations. Despite the widespread clinical use of IE, there is a notable absence of empirical reports about the nature of interoceptive assessments and IE. The present study was designed to describe the type, frequency, and typical anxiety extinction for a variety of interoceptive exercises typically used to treat panic disorder. Interoceptive assessment and IE data were compiled for patients with PD completing a CBT protocol. Data suggest that interoceptive assessment typically provokes fairly specific symptoms that often result in anxiety and even panic. On average, patients completed approximately 25 IE sessions during the course of treatment. Despite the use of a wide variety of interoceptive exercises, 4 exercises (hyperventilation, breathing through a narrow straw, breath holding, and spinning) accounted for the majority of IE sessions, and the majority of IE sessions led to within-session anxiety reduction.