Experimental pulmonary arteritis was produced in rabbits by intravenous injection of alveolar macrophages from donor rabbits. These animals, along with matched controls, were studied with pulmonary angiography to test the hypothesis that angiography could detect the vasculitic process in life. The animals were then sacrificed and postmortem angiography and histologic studies of the fixed inflated lung were used to locate the vascular lesions. The authors conclude that pulmonary vasculitis can be detected by angiography when the chest x-ray is normal.