Fifteen of 223 patients who have had extracardiac conduit repair at the Heart Institute of Japan from January, 1970, to April, 1991, have required conduits replacement because of conduit obstruction or infection. The main causes of obstruction were degeneration of the prosthetic valve and proliferative pseudo-intima in the conduit. The interval between initial conduit repair and conduit replacement was 2.2 to 18.3 years (mean 10.5 +/- 4.4). The average pressure gradient through the conduit decreased from 74.7 +/- 42.0 mmHg preoperatively to 12.3 +/- 7.1 mmHg postoperatively (p < 0.05). There was no early and late death. We concluded that xeno-pericardial roll conduits were superior to others and that conduit replacement procedure following the extracardiac conduit repair was safe and effective.