Ninety-one consecutive patients underwent radiofrequency ablation of chronic or paroxysmal atrial flutter. The average age of the patients was 66. There was a previous history of atrial fibrillation in 38% of cases and of cardiac surgery in 14.3% of cases. The primary success rate was 79% (92% in cases of common flutter). The predictive factors of success were the type of flutter (p < 0.001), left ventricular (p < 0.01) and left atrial dimensions (p < 0.01) at echocardiography. The length of the cavo-tricuspid isthmus measured by echocardiography had no influence on the initial result but, in primary success, did affect the parameters of the procedure (duration and number of applications of radiofrequency energy). After an average of 11 +/- 2 months, sinus rhythm was maintained in 67% of patients. There were recurrences of flutter in 27.5% of cases and of atrial fibrillation in 5.5% of cases: 85% of these episodes occurred during the first six months after ablation. A second procedure was carried out in 12 patients for recurrence of flutter (92% primary success rate). After an average follow-up of 8.4 months, 4 patients had a recurrence and required a third procedure (100% success rate). In cases of failure of ablation, the rhythm was converted by a shock or atrial pacing: 47.3% of these patients remained in sinus rhythm with antiarrhythmic therapy with a 12 month follow-up. Radiofrequency ablation of atrial flutter is, therefore, a safe method, the difficulty of which is mainly related to anatomical factors: the medium-term results are better than those of other therapeutic methods.