During the period from November 1989 to January 1992, 17 patients with ventricular tachyarrhythmias received an implantable pacemaker-cardioverter-defibrillator. The material consists of three female and 14 male patients with an age range of 13-66 years, mean 50.8 +/- 16.6 years. 13 patients had coronary artery disease, one cardiomyopathy, one a myocarditis sequela and two primary rhythm disorder. Four patients received epicardial and 13 endocardial electrode systems. The observation period varied from 4-30 months (april 1992), mean 15.2 +/- 8.8 months. 11 out of 17 patients (65%) experienced one or more episodes of tachyarrhythmias which was treated successfully with overdrive pacing (ramp or burst), cardioversion or defibrillation. One patient died of heart failure after an observation period of 13 months. His pacemaker-cardioverter-defibrillator had been activated more than 100 times. Two children, 13 and 15 years, were treated successfully for ventricular fibrillation four and five months after implantation of the device. The actual one year survival is 100%. Assuming that therapy with a device had not taken place, and that the six patients who experienced episodes of ventricular fibrillation died, the hypothetical probability of survival would have been 62.1 +/- 12.3%.