Abstract: Objective To evaluate the clinical effectiveness of β-blocker therapy on malignant ventricular arrhythmia in patients with acute myocardial infarction (AMI). Methods β-blockers, atenolol or betaloc, were given at the doses of 3.125 to 12.500 mg twice or 3 times a day (Bid or Tid) for management of malignant ventricular arrhythmia in 6 patients with AMI on the basis of conventional therapy. Increasing dosage of 25 to 50 mg was later initiated according to the patients’ condition. In 2 cases that failed to respond to conventional antiarrhythmic, esmolol was administered via intravenous injection (5-10 mg) to control malignant ventricular arrhythmia within approximately 30 min, followed by a 2-day course of intravenous infusion at the rate of 1 to 2 mg/min. Results Five AMI patients survived while death occurred in 1 case due to heart failure. No deterioration of the cardiac function or proarrhythmic effect was observed in the 5 survival cases, but the occurrence of transient hypotension in 2 cases in the early stage of β-blocker application and death due to cardioc insufficiency in one. Conclusion Adequate use of β-blockers is necessary in the early stage of AMI for effective control of malignant ventricular arrhythmia and lowering the mortality.