We compared the results of 43 patients with W.P.W. syndrome operated respectively between 1975 and 1980 (group I) and after 5/1/1983 (group II). Groups were comparable in size (n = 19 & 28), mean age (38 & 34 years), indications and percentage of left or right free wall accessory pathways (AP) (12/19 and 16/28). Only conventional surgical techniques were used, without physical agent. In group I, we observed 3 surgical deaths, 4 initial failures and 12 with success. Two patients were reoperated after failure, 1 with success, and 1 with a final failure. The final success rate was 13/19. In group II, we observed 1 surgical death, 1 failure and 26/28 success. In patients with paraseptal right or left AP, an improvement of the surgical approach is clear: we had 3 initial failures on 7 cases in group I, contrasting with 1 failure in 12 cases of group II. However, difficulties persisted in patients with multiple AP. It represents only 1 case in group I (left lateral + posterior AP), which was recognized before surgery and successfully treated. In group II, 3 patients had multiple AP: 1 with left & right posterior AP, known before surgery and operated with success, and 2 with left lateral & posterior, not detectable even on the intraoperative epicardial mapping, with 2 failures. One was controlled by His bundle fulguration, and the other was reoperated within the same procedure and died from myocardial ischemia due to extensive dissection. An improvement of surgical techniques is obvious between 1980 and 85, especially for dissection of paraseptal AP. Presence of multiple AP remains the major problem of this surgery. Development of physical agents (cryosurgery or laser) may improve the results, allowing a less extensive dissection of the AV groove.