The Irrational Health Belief Scale (IHBS) assesses the tendency to appraise health-related information in an irrational manner. Despite the central role that dysfunctional assumptions about health play in the cognitive-behavioral model of hypochondriasis and health anxiety, researchers have not examined the relation between health anxiety and the types of irrational health beliefs assessed by the IHBS. Two samples (n = 198, n = 295) of students completed the IHBS and measures of anxiety and health anxiety. In both studies, the IHBS was correlated with health anxiety, and this association was mediated by anxiety. These findings suggest that the range of dysfunctional beliefs associated with health anxiety is greater than was initially described by the cognitive-behavioral model. © 2010 Wiley Periodicals, Inc. J Clin Psychol 00:1–12, 2011.