BACKGROUND Whether the bidirectional Glenn procedure is better performed without the support of cardiopulmonary bypass is still a matter for debate. In this paper we discuss the indications and methods for bidirectional Glenn shunt without cardiopulmonary bypass. METHODS Twenty patients with complex cyanotic congenital heart defects underwent a bidirectional Glenn shunt without cardiopulmonary bypass between May 2000 and August 2002. There were 10 male and 10 female patients, the mean age was 2.7 +/- 2.6 years (range, 3 months to 11 years), and the mean weight was 11.0 +/- 6.0 kg (range, 4.5 to 32 kg). The mean transcutaneous oxygen saturation was 74.3% +/- 5.7% before the operation. The Glenn shunt was performed under venoatrial or venopulmonary shunt. RESULTS All patients survived. Mean superior vena cava clamping time was 24.3 +/- 4.7 minutes, and mean vena cava pressure was 26.9 +/- 5.5 mm Hg during clamping. There were no postoperative neurologic complications. Follow-up echocardiography showed functioning Glenn shunts without any obstruction at the anastomosis. CONCLUSIONS The adverse effects of cardiopulmonary bypass could be eliminated by this method. This is an advantage during the postoperative recovery, but patients should be strictly chosen.