One hundred thirty patients presenting at an anxiety disorders research clinic were administered a structured interview (i.e., Anxiety Disorders Interview Schedule-Revised). Diagnoses were made in accordance with Diagnostic and Statistical Manual (rev. 3rd ed.) criteria. Seventy percent of patients received at least one additional but secondary Axis I diagnosis. The most common additional diagnoses were simple and social phobia, which were assigned to nearly one third of all patients. In addition, 33% of anxiety disorder patients received an additional diagnosis of a depressive mood disorder (i.e., dysthymia or major depression). The distribution of specific additional diagnoses are presented for each principal anxiety disorder category. The scientific and clinical implications of comorbidity are discussed while considering the relatively high patterns of syndrome comorbidity found in the present study, which is consistent with several earlier studies.