In a prospective study, 100 consecutive patients (mean age 51.3 years) with angina pectoris had propranolol abruptly discontinued 24 to 144 hours (mean 39.0 hours) prior to elective coronary arteriography. The mean duration of therapy was 8.2 months and the mean daily propranolol dose was 216.1 mg. New York Heart Association Class II, III and IV symptoms were present in 30, 41, and 29 patients and one, two, or three coronary arteries were more than 50 per cent narrowed in 37, 29, and 34 cases, respectively. Three patients experienced minor increases in chest pain and two suffered non-transmural myocardial infarctions prior to the time of scheduled cessation of therapy. The same number of minor and major complications occurred in the post-withdrawal period. All four patients who developed non-transmural myocardial infarction in this study had pre-existing Class IV symptoms. The course of the remaining 90 patients was uneventful. These findings do not support the concept of a rebound propranolol withdrawal reaction.