Little is known about factors that mediate the relationship between anxiety and respiratory-related distress and disability. We hypothesized that elevations in anxiety sensitivity would be associated with greater severity of dyspnea, greater dyspnea-related avoidance, and poorer subjective assessment of health in patients with dyspnea referred for pulmonary function testing, regardless of objective evidence of pulmonary dysfunction. A total of 182 consecutive patients receiving pulmonary function tests to evaluate dyspnea were screened with a patient-rated Primary Care Evaluation of Mental Disorders and completed the Anxiety Sensitivity Index and questionnaires assessing symptom severity and avoidance. Anxiety Sensitivity Index score predicted more severe subjective dyspnea and greater dyspnea-related avoidance, even after adjustment for anxiety disorders and pulmonary dysfunction. Despite some limitations, these data provide preliminary support that strategies to identify, measure, and address high levels of anxiety sensitivity should be examined to reduce subjective distress and improve functioning for patients with dyspnea.