The aim of the study was to estimate the efficacy and complications of the first ablations of atrial fibrillation (AF) performed in a single teaching institution. The first 100 consecutive patients with symptomatic paroxysmal, persistent or permanent AF treated by application of radiofrequency in the left atrium, were included. In the patients with paroxysmal AF, success was judged as complete in 21 out of the 35 (60%). The benefit was lower in patients with persistent arrhythmia (19 out of 42, 45%). In the 23 patients with permanent AF, there were 16 failures (69%) with recurrence of AF in 10 patients the day after the procedure. There were 13 patients (13%) with minor complications.