The authors report on the effects of propranolol, a beta-adrenergic blocking agent, on 10 patients with pathological panic states. Propranolol was effective in treating acute pathological panic, but modest doses of the drug administered for brief periods of time did not alleviate chronic panic attacks associated with agoraphobia. The drug suppressed panic associated with depressive syndromes but did not affect the depression and had no clear effect on anticipatory anxiety. The authors suggest that further study of these findings may clarify other clinical problems.