30 patients (mean age 56 +/- 18 years) suffering from multiple ventricular extrasystoles (VES) of various origin, like ischemic, hypertensive, valvular and congenital cardiopathy, and arrhythmogenic ventricular dysplasia, were treated during 12 days by a daily dose of 900 mg of propafenone (15 cases) or 600 mg of amiodarone (15 cases). The study was randomized and a portable ECG was used for 24 h. At the time of entering into the study (H0) the patients were without any therapy. The mean total number of VES was 16,878 +/- 9,212 in the propafenone group (2,062 +/- 2,342 of them being repetitive) and 19,497 +/- 7,930 in the amiodarone group (2,907 +/- 3,615 of them being repetitive). The difference between the two groups was not statistically significant, even with the use of Holter (H1) ECG monitoring one week later. After 12 days of treatment (H2) a significant decrease in the number of total VES was noted: by 78% with propafenone (76% isolated and 89% repetitive VES) and by 77% with amiodarone (74% isolated and 91% repetitive VES). The difference between the effect of the two drugs was not significative. After 12 days of wash-out (H3) the number of VES returned to initial values with propafenone but not with amiodarone where the values were still decreased after 82 days of wash-out (H4). Both drugs produced significant bradycardia which was more apparent and more spread out during the nyctohemeral with amiodarone. Propafenone affected rather the maximal and diurnal frequencies. No correlation was found between the bradycardic and antiarrhythmic effect. Amiodarone was well tolerated and propafenone produced minor digestive and neurosensory troubles in about half the cases, only in one patient a more pronounced arrhythmogenic effect was observed. In conclusion, the efficacy and the good hemodynamic tolerance of the two drugs was found to be similar in the short-term treatment of chronic, isolated or repetitive VES, irrespective of their etiology.