In 6 patients (mean age 49 +/- 11 years) with chronic recurrent ventricular tachycardia which were relatively slow during antiarrhythmic therapy and had been proven to be resistant to various antiarrhythmic drugs, catheter ablation of the site of origin of ventricular tachycardia was performed after endocardial activation and/or pace-mapping. According to the results of catheter mapping, the sites of origin of ventricular tachycardia were in the region of the infero-lateral wall (n = 3), in the anterolateral wall (n = 1) and in the right ventricle (n = 2). In 3 cases, two ablative procedures were performed as the first was only transiently successful. A total of 51 shocks was delivered (200 J 45 times, 100 J 5 times and 400 J once). The following complications were observed: multiple episodes of spontaneous, partly polymorphous ventricular tachycardia which degenerated into ventricular flutter on several episodes (n = 1); transient third degree AV-block and intermittent complete right bundle branch block (n = 1); transient ST-elevation (n = 3); and self-terminating atrial tachycardia lasting for several minutes (n = 1). Immediately after the first ablative procedure, either no ventricular tachycardia could be induced any longer (n = 2) or non-clinical ventricular tachycardia was induced (n = 2). In the remaining 2 patients, programmed ventricular stimulation was not repeated immediately at the end of the ablative procedure. During a follow-up study at the end of the first week, the clinical ventricular tachycardia could be induced again in 3 of 4 cases. In 3 cases, a second ablative procedure was performed because of recurrences of ventricular tachycardia (n = 2) or syncope (n = 1). During final follow-up (mean 4.3 +/- 3.4 months), no recurrences of ventricular tachycardia were observed in 5 cases. In one case, recurrences occurred. Therefore, an automatic cardioverter was implanted. In conclusion, these preliminary results show that catheter ablation of drug-resistant ventricular tachycardia is feasible and may be an alternative to surgical procedures.