Anxiety sensitivity (i.e., fear of anxiety-related symptoms due to the belief that these symptoms will produce harmful consequences) is an important psychological construct involved in the etiology of different anxiety disorders. The present study evaluated the psychometric proprieties and the factor structure of the Anxiety Sensitivity Index-Revised (ASI-R) among 585 Brazilian patients with primary anxiety disorder diagnosis. Results indicated that the present version of the ASI-R had good internal consistency and item-total correlation coefficients. Exploratory factor analyses suggested a hierarchical structure composed by a single higher-order factor and four lower-order factors related to 1) fear of respiratory and cardiovascular symptoms, 2) fear of cognitive dyscontrol, 3) fear of publicly observable anxiety reactions, and 4) fear of gastrointestinal symptoms. ASI-R higher- and lower-order factor scores comparisons across the different anxiety disorder groups indicated that panic disorder patients scored significantly higher in the ASI-R dimensions, except for the fear of cognitive dyscontrol lowerorder factor.