The central pulmonary artery was studied angiographically 1-10 years after a palliative operation in 56 patients (mean age 6 years, range 1-20) with congenital heart disease and pulmonary atresia. All of them had originally had a central pulmonary artery that was common to both the right and left pulmonary arteries. Juxtaductal obstruction of the left pulmonary artery had developed in 70% of the patients; in 40% the obstruction was atretic unilaterally. Atresia developed at the right junction to the ductus where there was a shunt to the right pulmonary artery and at the left junction where there was a shunt to the left pulmonary artery. Stenosis causing a reduction of more than 50% of the inner diameter developed at the anastomotic site in 10% of 30 patients with a functioning Blalock shunt. In contrast, there was occlusion of the pulmonary artery or its upper branch in 73% of 11 patients with a non-functioning anastomosis.