We studied the efficacy of propranolol (Inderal) compared to alprazolam (Xanax) in 29 patients with a diagnosis of agoraphobia with panic disorder or panic disorder with or without limited phobic avoidance in a 6-week double-blind controlled experiment. Alprazolam is effective in those syndromes, whereas to date only negative or ambiguous results had been reported for propranolol. Fourteen patients received a mean daily dose of 5.0 +/- 2.3 mg of alprazolam and 15 patients received 182.0 +/- 60.5 mg mean daily dose of propranolol. We found both drugs to be effective to suppress panic attacks and reduce avoidance behavior. The only significant between-drug difference was a more rapid onset of alprazolam's panicolytic effect. Propranolol merits further study. We suggest patients worthy of a clinical trial.