Ventricular ectopic activity is commonly encountered in clinical practice. Usually it is not associated with life-threatening consequences in the absence of significant structural heart disease. However, frequent ventricular ectopic beats can be highly symptomatic and even incapacitating in some patients. Currently, reassurance and pharmacological therapy are the mainstays of treatment. This study assesses the useful role of catheter ablation in eliminating drug refractory monomorphic ventricular ectopic beats in severely symptomatic patients. Eight patients were included, five patients had no heart disease and in three patients a structural heart disease was present (coronary artery disease in 1, hypertensive heart disease in 1, mitral valve prolaps in 1). The ejection fraction was higher than 40% in all patients (mean EF 56 +/- 14%). Mean number of ventricular ectopic activity was 29,295 +/- 10,650 VPB/24 h (1209 +/- 457 VPB/h) before ablation. No other spontaneous or induced arrhythmias were documented. The site of origin of ventricular ectopic activity was accurately mapped by using earliest endocardial activation time during ectopic activity or pace mapping, or both. The ectopic focus was located in the right ventricular outflow tract in five patients and in the left ventricle in three patients (posteroseptal 2, anterolateral 1). Frequent ventricular ectopic beats were successfully eliminated by catheter ablation in all patients. Early recurrence occurred in one patient after 10 min and 30 min after the procedure. In another patient a recurrence occurred 6 days after the procedure. In a second session he was successfully ablated and remained free of recurrence since 2 months. After ablation the mean number of ventricular premature beats was 211 +/- 159 VPB/24 h (9 +/- 7 VPB/h). The mean number of radiofrequency applications was 8 +/- 7 (range 2-22). Mean radiation time was 12 +/- 8 min. No complications were observed. During a mean follow-up of 6 months there were no further recurrences in the remaining six patients. Radiofrequency catheter ablation can be successfully used to eliminate monomorphic ventricular ectopic activity. It may therefore be a reasonable alternative for the treatment of severely symptomatic, drug resistant monomorphic ventricular ectopic activity.