In this retrospective study of 22 patients with the Wolff-Parkinson-White (WPW) syndrome, the cost of catheter ablation in 11 patients was compared with that of surgical ablation in another 11 patients. All patients in the catheter ablation group had a posteroseptal accessory pathway; in the surgical group, 5 patients had a left lateral accessory pathway, 3 had a left lateral and posteroseptal accessory connection and 3 had a right-sided pathway. Catheter ablation was successful in 8 of 11 patients (73%). In the surgical group, the accessory pathway was interrupted successfully in all patients (100%). The mean duration (+/- standard deviation) of hospitalization was 6 +/- 2 days in the catheter ablation group and 8 +/- 4 days in the surgical group. The mean cost/patient, expressed in 1988 dollar values, was +14,116 +/- 4,493 in the catheter ablation group and +34,175 +/- 5,434 in the surgical ablation group (p less than 0.0001). The mean time lost from work or school was 10 +/- 5 days in the catheter ablation group and 60 +/- 16 days in the surgical group (p less than 0.01). Catheter ablation is significantly less expensive than surgical ablation of accessory pathways. Assuming that all patients in whom catheter ablation is unsuccessful subsequently undergo successful surgical ablation, the mean cost of definitive therapy in the catheter ablation group (+24,382 +/- 4,741) is still significantly lower than the cost in the surgical group (+34,175; p less than 0.001). An additional economic advantage of catheter ablation is that the mean time lost from work or school is 10 days compared to 60 days with surgical ablation.