We implanted the automatic implantable defibrillator model B (AID-B) in 11 patients (pts). Seven pts had coronary disease with sustained VT, and/or VF. Two had syncopal VT due to primary cardiomyopathy, and two pts had syncopal torsades to pointes (Tdp) without cardiac disease (1 long QT syndrome). These arrhythmias occurred despite antiarrhythmic drugs or beta blockers. Four pts had implanted: an epicardial patch by thoracotomy, an intra-atrial string electrode by the jugular vein, then AID-B by abdominal route. In 7 pts, subcostal approach was used, for implanting simultaneously 2 epicardial patches and the AID-B itself. During the operation, VT, Tdp and/or VF were induced in all pts by 50 Hz alternating current. The defibrillation threshold (DT) between atrial catheter and epicardial patch was < 15 J in 4 pts, and > 25 J in two, requiring a larger patch in 1, and replacement of atrial electrode by another patch in the 2nd pt to obtain a DT < 20 J. In the 6 pts implanted with 2 patches, DT was always < 25 J. In 3 pts, DT was markedly higher for VF (25 J) than for VT (< 15 J). One pt died from pulmonary embolism, another died after 3 years, before replacement of a failing battery, and a third died from progressive congestive heart failure, 6 months later. Eight pts are alive with a follow-up > 6 months. Local aseptic reactions obliged a removal of the implant in 2 pts operated by bifocal approach, and none when the subcostal route was used. Six pts had 2-55 spontaneous shocks, accurately delivered, as shown by Holter recordings. In one case, elective replacement of the device was needed by end of life of the battery after 2 years. AID-B appears safe and effective for treatment of malignant ventricular arrhythmias. The subcostal route avoided local problems. Use of 2 patches decrease DT.