The demonstration in preclinical studies that centrally administered neuropeptide Y (NPY) has anxiolytic effects had led to speculation that NPY may play a role in human anxiety disorders. We therefore decided to study plasma NPY levels in 22 patients with DSM-III-R anxiety disorders (11 with panic disorder and 11 with social phobia, generalized type) and 12 never psychiatrically ill comparison subjects. Under resting conditions, plasma NPY levels did not differ among the three diagnostic groups. Following hand immersion in ice water, plasma NE levels--but not NPY levels--increased immediately, but there were no significant differential diagnostic effects. These results are convergent with prior reports of normal sympathetic nerve activity in patients with anxiety disorders.