To assess proarrythmogenic effects after different techniques of radiofrequency catheter ablation, 427 patients with paroxysmal, persistent, and long-standing persistent atrial fibrillation (AF) were examined. The patients were randomized into four groups: antral pulmonary vein isolation (PVI) (Group I), PVI plus roof line and mitral isthmus ablation (Group II), anatomic ablation of ganglionated plexuses (GP) of the left atrium (Group III) and GP plus PVI (Group IV). At the end of follow up (34,43,2 months) the largest number of proarrythmogenic effects was observed in Group II, 24,8% (26 patients). In the remaining groups the percentage of proarrythmogenic effects did not exceed 11%, neither was there any significant difference among Groups I, III and IV. Thus, the creation of additional linear lesions in the left atrium is a predictor of proarrythmogenic effects during follow up.