Lung specimens of 27 patients under six months of age with complete transposition of the great arteries (TGA), obtained at autopsy, were studied histologically. No evidence of hypertensive pulmonary vascular disease was found in patients under four months of age (23 patients), while obstructive intimal proliferations were seen in 2 patients, aged four and five months, with TGA and VSD. Since pulmonary vascular lesions in transposition with VSD appear early in infancy, timely palliative procedures, such as banding of the pulmonary artery, are strongly indicated when the radical corrective operation is to be postponed.