A case of pulmonary veno-occlusive disease in an adult is presented. The diagnosis was suspected clinically and verified at cardiac catheterization. Balloon dilatation of the pulmonary veins was attempted at operation and later again in the catheterization laboratory. The result was a significant reduction in pulmonary venous to left atrial pressure gradient and angiographic evidence of increase in venous diameter. It appears that in the focal form of pulmonary venous occlusion, balloon dilatation may offer a therapeutic approach in an otherwise progressively lethal disease.