It is known that intermittent dobutamine therapy improves the symptoms and physical condition of patients with chronic heart failure, but its arrhythmogenic effect is insufficiently described. The aim of this study was to assess ventricular arrhythmias and the condition of patients before, during, and after intermittent dobutamine therapy. The 23 patients participating in the study were in New-York Heart Association functional classes III and IV despite therapy with digitalis, diuretics, and angiotensin-converting enzyme inhibitors. Starting dosage of dobutamine was 2 μg/kg/min, which was raised gradually up to 12 μg/kg/min, or until the appearance of complaints or symptoms. In group I (7 patients), for 24 hours before dobutamine infusion, Holter monitoring had been performed. In the subsequent 24 hours, during the infusion, patients were monitored in the critical care unit, but the second Holter test was performed only after the infusion, i.e., in the third 24 hours. In group 11 (16 patients), the Holter monitoring was started 4 hours before dobutamine infusion and was continued for an additional 20 hours, during the drug administration. In the 24 hours after dobutamine treatment, another Holter monitoring was performed. There was no increase in frequency of ventricular arrhythmias after the dobutamine infusion compared with the preinfusion period, but during dobutamine administration, ventricular arrhythmias occurred more frequently than in the preinfusion and postinfusion periods. No ventricular fibrillation was observed in the 23 patients. In conclusion, ventricular arrhythmias are frequent in congestive heart failure, and dobutamine infusion increases their incidence. The arrhythmogenic effect of dobutamine subsides on the day after the dobutamine infusion. Because of the arrhythmogenic effect of dobutamine, admission to the critical care unit is suggested during the infusion, but monitoring is not necessary after the end of the infusion.