Recent advances in psychiatric nosology have provided a clearer clinical description of panic disorder and agoraphobia with panic attacks. This clinical improvement has yet to result in a better understanding of the basic mechanisms involved in these conditions. The present study compares the effects of the cold pressor test on blood pressure changes and prolactin levels in patients with panic disorder and agoraphobia with panic attacks to its effects in normal controls. Because the effects of the cold pressor test were similar in patients and normal controls, it appears that alpha-adrenergic function is normal in the patient group. The results also suggest that prolactin hypersecretion does not occur in pathological anxiety states.