Catheterization of the aorta through the umbilical artery and/or of peripheral arteries in neonates may be accompanied by a number of complications, of which thrombotic phenomena and peripheral vasospasm are the most common. Two neonates with peripheral ischemia caused by vasospasm from indwelling umbilical artery catheterization and one infant with left hand ischemia due to a left radial artery line were successfully treated with 2% nitroglycerin ointment. No adverse effects were noted.