We report our results with 14 cases of tetralogy of Fallot, which were treated with a modified Blalock-Taussig shunt first, total correction having been performed in 9 of them after a mean interval of 15 months. The age of the patients ranged from 12 days to 3.3 years, with a mean of 4.7 months in 12 patients below the age of one year. In 11 cases we used a 5 mm Gore-Tex prosthesis, in 2 a 6 mm prosthesis and in one a 4 mm prosthesis. All children survived the operation. In one case shunt thrombosis occurred after a bout of pneumonia and a second shunt had to be constructed on the other side. Control angiography, performed after a mean period of 15 months in 13 patients revealed a patent shunt, though angulation of the ipsilateral pulmonary artery was noted in one case. The ratio of the diameter of the pulmonary artery to the aorta increased by 20%. The significance of these findings with regard to the question of primary or two-stage repair in infants less than one year old is discussed in view of different risk factors.