Introduction: Transcatheter closure of interatrial communications (ASD) with Amplatzer occluders (ASO) became standard treatment in many centers. We analyzed the incidence of cardiac arrhythmias after such treatment. Methods: The group of 759 patients (pts) after transcatheter closure of ASD with ASO were retrospectively analyzed. Only pts with a new and symptomatic arrhythmias were included to the study. All pts, who had arrhythmias prior to ASD closure, were excluded. Results: New tachy- and bradyarhtymias after implantation of ASO were observed in 11 pts (1,5%). There were 9 pts (mean age 36,7 y) with atrial tachyarhythmias (AF in 8 and SVT in 1 pt), which appeared between 1 day and 3 months after implantation. Seven pts were treated initially by pharmacotherapy; in 2 of them sinus rhythm returned just after cardioversion. In another 2 cardioversion was performed as initial therapy. In non but one recurrence of tachycardia was observed, however 7 of them had prolonged (till one year) pharmacotherapy. In 2 pts aged 15 and 16 years complete a-v block appeared 4,3 and 1,5 year after ASO implantation respectively. In the first one intermittent II degree a-v block (Mobitz II) was observed before ASD closure. DDDR pacemaker was implanted in both pts. Conclusions: Transcatheter closure of ASD with ASO is associated with the risk of new atrial tachyarythmias (usually early after the procedure and in older patients). The risk of complete heart block is low, but it can appear in late follow-up. Thence close long term follow-up of all patients is obligatory.