The characteristics of multiple accessory pathways in children have not been previously studied. Records were reviewed of 317 consecutive pediatric patients with Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency catheter ablation at our institution. Twenty-eight patients (9%) had multiple pathways (a total of 64 pathways: 21 patients had 2, 6 had 3, and 1 patient had 4 pathways). The locations were left free wall (22 pathways), right free wall (19 pathways), posteroseptal (17 pathways), and anteromidseptal (6 pathways). Of these 64 pathways, 55 were ablated successfully without complications, 5 failed ablation, and 4 fasciculoventricular fibers did not require treatment. Three patients had a newly found pathway at the repeat session. Three patients had atrioventricular nodal reentrant tachycardia and the slow pathway area was modified. One patient had failed initial ablation and had a successful ablation using a 3-dimensional electroanatomic mapping system. Compared with patients with a single pathway, those with multiple pathways exhibited a higher incidence of antidromic tachycardia, a shorter anterograde accessory pathway effective refractory period (<250 ms), a longer fluoroscopic time (65 +/- 43 vs 39 +/- 46 minutes, p <0.05), and a larger number of unsuccessful attempts (9 +/- 16 vs 5 +/- 8, p <0.05). Success rate (92% vs 93%) and recurrence rate (1.7% vs 2.1%) were similar in both groups. This study demonstrates that multiple pathways are not rare in pediatric patients and that multiple pathways contrast with a single pathway in a variety of conduction properties.