The close association of the external and internal carotid circulations in the orbital cavity is well recognized. Two cases are presented in which local trauma to the orbit apparently resulted in the formation of an arteriovenous fistula. These lesions progressively expanded, producing classical features of proptosis, chemosis, and bruit. The investigation by selective angiograms and the surgical management of these malformations are discussed. A further case is presented in which an early lesion was noted in angiography after a head injury, with subsequent disappearance of the lesion some weeks later.