The aim of this study was to analyse the efficacy and survival after implantation of an automatic cardioverter-defibrillator.. Forty-five patients including 37 men were followed up for 0 to 51 months. The indications were ventricular fibrillation with no curable cause (n = 27) and sustained resistant or poorly tolerated ventricular tachycardia (n = 17) when programmed ventricular pacing with antiarrhythmic therapy was not applicable or gave poor results. One patient was implanted with this device for torsades de pointes. The underlying cardiac disease was ischaemic in 34 cases, non-ischaemic in 8 cases, and 3 patients had no apparent cardiac disease. Twenty patients were implanted with an epicardial system (group I) and 25 patients with endocardial system (group II). In group II, there was one complete failure of implantation requiring the use of an epicardial system and 2 partial failures requiring an additional epicardial patch electrode. The perioperative mortality was 2/45 (4.4%), both cases being due to permanent arrhythmias. In 5 patients, the minimal effective energy of defibrillation was over 25 Joules at implantation, without any untoward consequences on the clinical outcome. Ten non-fatal complications were observed including two major problems (haemopericardium); there were two cases of late increase of the minimal effective energy of defibrillation requiring the addition of a subcutaneous patch. Twenty-four patient (53%) received at least one appropriate therapy; 14 patients (36%) had at least one inappropriate shock during follow-up. During follow-up, 7 patients died, 6 of a cardiac cause and 3 of an arrhythmic problem.(ABSTRACT TRUNCATED AT 250 WORDS)