Feasibility of RF ablation using a simplified two-catheter technique from a femoral approach was studied in 97 consecutive patients with a manifest or concealed accessory pathway located at the anteroseptal, mid-septal, and para-Hisian areas. RF was applied at the site with the shortest V-delta interval or the earliest retrograde atrial activation during orthodromic tachycardia or right ventricular pacing. Ablation was initially successful in 88 of 97 patients (91%). Success rate was 94% (16/17) for anteroseptal, 94% (39/43) for para-Hisian, and 89% (33/37) for mid-septal accessory pathways, without differences between manifest and concealed pathways for any of the locations. Mean number of RF pulses was 8 +/- 5 for anteroseptal, 6 +/- 6 for mid-septal, and 12 +/- 13 for para-Hisian accessory pathways. Two patients (2%) required implantation of a permanent pacemaker for complete AV block. At a mean follow-up of 27 +/- 14 months, four patients with previous manifest preexcitation experienced resumption of intermittent preexcitation, but only one required a second successful procedure for recurrence of palpitations. RF ablation can be used effectively and without impairment of normal AV conduction in the majority of patients with anteroseptal, para-Hisian, and mid-septal accessory pathways using a simplified two-catheter technique from a femoral approach.