The optimal procedure for shunting palliation in cyanotic infants remains to be determined. Sixty-two infants less than 3 months of age underwent 63 modified Blalock-Taussig shunts. Their age range at operation was 1 to 84 days (mean, 16 +/- 20 days). Shunts were constructed using 5-mm polytetrafluorethylene tubes in 20 patients and 4-mm polytetrafluoroethylene grafts in 43 patients. There were 13 early deaths (21%; CL, 15% to 27%) of which three deaths (5%; confidence limits, 2% to 9%) were shunt related. The survivors were followed up from 6 to 53 months (mean, 29 +/- 12.5 months). Shunt failure (occlusion, inadequate palliation) occurred in 27 patients. The overall probability rate of adequate shunt function was 58% +/- 8% at 2 years. Univariate and multivariate analyses showed that the size of the graft was a risk factor of shunt failure. Severe distortion of the pulmonary arterial branch was noted in 12 patients. The inferences are: (1) modified Blalock-Taussig shunts provide satisfactory early palliation but late shunt failure is frequent; (2) similar results should be obtained with other shunting procedures; and (3) the optimal procedure should be selected for each cyanotic infant on an individual basis.