In our study, we aimed at compare both retrograde and transseptal approaches as regards; success rate, complications, procedure and ablation time, number of ablation attempt and recurrence of symptoms during follow up for 6 months in 23 symptomatic patients with AVRT or AF utilizing left sided accessory pathway. All patients underwent full clinical evaluation as regards history taking, clinical examination, resting ECG and ECG during tachycardia if available, echocardiography and full electrophysiological study to confirm presence of a left sided accessory pathway. Patients are randomly divided into two groups according to the approach we start. Retrograde group : when the retrograde approach was attempted at first. Transseptal group : when the transseptal approach was attempted at first.In case of failure of one approach the other approach is attempted (crossover technique) in the same session or in another session.