The purpose of our study was to evaluate the therapeutic and preventive action of propafenone on ventricular hyperkinetic arrhythmias (VHAs). 26 patients with VHAs have undergone a follow-up over a period of 90 days. Controls by means of dynamic electrocardiography (Holter) took place in baseline condition and on the 30th, 60th and 90th day of treatment. All patients were initially treated with 450 mg of P daily. According to the result of the first and second control, the P dosage was increased to 600 and 900 mg for those patients who failed to show any improvement. 88% of the patients showed a considerable improvement: 69% were free from arrhythmias and 33% exhibited a significant reduction. At the dose of 450 mg, P proved to be effective in 72% of cases; in the follow-up period a further increase in the effectiveness of the treatment was observed. The same trend resulted also from the observation of the patients treated with 600 and 900 mg. We can therefore confirm the effectiveness and tolerability of P as a first choice treatment of VHAs.