Between December 1986 and December 1990, a bidirectional cavopulmonary anastomosis was performed in 27 patients younger than 2 years of age, including 12 with heterotaxia syndrome. Age and weight of patients averaged 14.2 +/- 6.6 months and 8.1 +/- 2.2 kg, respectively. Eleven had pulmonary atresia and 16 had pulmonary stenosis. The main pulmonary artery was ligated in seven patients in the latter group (subsequently reopened in one) and left open in nine (subsequently ligated in two). There were four hospital deaths (15%). All patients were discharged with anticoagulant/antithrombotic therapy to be continued for 6 months. There were two late deaths before further operations (8.7%). Two patients, one with acquired massive pulmonary arteriovenous fistulas and one with progressive common atrioventricular valve regurgitation, subsequently underwent definitive repair (biventricular in one), and both died. Heterotaxia syndrome (p = 0.087) and preoperative mean pulmonary artery pressure higher than 15 mm Hg (p = 0.09) were the only risk factors for overall mortality.