We have analyzed 36 newborns (19 males and 17 females), with cyanotic cardiopathies in whom a systemic-pulmonary shunt had been performed. These patients were admitted to the Neonatal Intensive Care Unite between January 1985 and June 1990. We studied the perioperative events with the aim of describing the general features of this palliative surgery in the neonatal period and to determine the factors which indicate a bad prognosis. The age at admission was 10.5 +/- 16.5 days and at surgery was 19.5 +/- 20 days. Cardiopathy types included: 13 pulmonary atresias, 9 pulmonary stenoses, 6 D-transposition of the great arteries and 8 tetralogies of Fallot. Of these patients, 83% required prostaglandin administration before surgery. Cardiac catheterization was performed in 54% (in 1/3 balloon atrioseptostomy was performed). The mean diameter of the pulmonary branches was 3.5 +/- 0.7 mm. In 89%, a modified Blalock-Taussig shunt and in 11% a central aorto-pulmonary shunt were performed. The size of the prosthetic graft used was 4 mm in diameter in 77% of the cases, 5 mm in 20% and 3 mm in 3% of the patients. The mortality rate was 27% (intraoperative = 0%, early postoperative = 16%, late postoperative = 11%) with two critical periods: the initial 48 postoperative hours and the reoperation. Bad prognosis factors related to mortality are; preoperative (shorter gestational age and low newborn weight), operative (performance of a central aortopulmonary shunt, surgical ligation of the ductus during operation) and postoperative (arrhythmias, metabolic acidosis in the immediate postoperative period, lower oxygen saturation at 24 hours after the operation, hemorrhage). Our data are compared with other reports of systemic-pulmonary shunt in the neonatal period.