Although anxiety disorders have been associated with impairments in self-reported health functioning, the relative effect of various anxiety disorders has not been studied. We compared health functioning of patients with a principal diagnosis of posttraumatic stress disorder (PTSD), panic disorder (PD), generalized anxiety disorder (GAD), and major depressive disorder (MDD). Patients with PTSD and MDD were equally impaired on overall mental health functioning, and both were significantly worse than patients with PD and GAD. PTSD was associated with significantly worse physical health functioning relative to PD, GAD, and MDD. Hierarchical regression showed that the association of PTSD with physical health functioning was unique and was not caused by the effects of age, depression, or comorbid anxiety disorders. Both PTSD and comorbid anxiety accounted for unique variance in mental functioning. These results highlight the association of PTSD with impaired physical and mental functioning and suggest that effective treatment of PTSD may affect overall health.