To evaluate the prevalence of intermittent opacification, a finding previously described as diagnostic of active bleeding that allows identification of an injured vessel at initial aortography or first-order selective angiography. Retrospective review was performed of 35 consecutive cases that were positive for true or false aneurysm, arteriovenous fistula or malformation, or hemorrhage when a lesion was located beyond a first-order branch of the aorta. An artery that potentially supplied the lesion was considered positive if it filled with contrast material, emptied, and filled again while adjacent vessels demonstrated progressive opacification. Nine (26%) of the 35 cases demonstrated intermittent opacification of an injured artery. All were confirmed as true-positive with superselective catheterization or additional projections, and seven were successfully treated with transcatheter embolization. Intermittent opacification was associated only with false aneurysm and hemorrhage. No congenital arteriovenous malformations or congenital aneurysms demonstrated intermittent opacification. If present, the intermittent opacification of an artery is a valuable finding that assists in superselective transcatheter embolization of the arterial branch that supplies a false aneurysm or hemorrhage.