The aim of this retrospective study was to assess short and long-term mortality and morbidity after radiofrequency ablation of the atrioventricular junction in patients with supraventricular arrhythmias resistant to treatment. This cooperative series included 91 patients (47 men, mean age 68 +/- 9 years). The arrhythmia was paroxysmal in 56% of cases. The mean duration of symptoms was 67 +/- 61 months and 45 patients (49.4%) were in the NYHA Classes III and IV. An escape rhythm was present in 58 patients with a mean frequency of 39 +/- 9/min. Early complications were observed in 5 patients (venous thromboses, pulmonary embolism, mild pericardial effusion and haemothorax). The hospital mortality was 4 patients (4.4%). Death was of cardiac origin in 1 case (cardiac failure). The mean follow-up of patients was 14.5 +/- 8.6 months. Eleven patients died during this period, 8 of cardiac causes: cardiac failure (3 cases), sudden death (3 cases), thrombosis of a valve prosthesis (1 patient) and major electrolyte disturbances causing loss of stimulation in 1 case. Six patients had recurrences. Long-term morbidity was either related to cardiac pacing (3 cases) or cardiac failure (3 cases). Thirteen patients were in NYHA Classes III or IV at the end of follow-up. The authors conclude that radiofrequency ablation at the atrioventricular junction is an effective method of treating resistant supraventricular arrhythmias. Complications are not frequent but mortality appears to be high, probably due to the presence of advanced cardiac disease in the majority of cases. Sudden death seems to be rare and unrelated to pacing defects.