An arterial connection between the two internal ophthalmic arteries in the rabbit was confirmed. The consensual response to ocular injury and its relationship to this interconnecting artery was examined by transecting the interconnecting vessel and creating a monocular injury by anterior chamber paracentesis. In the rabbits of two control groups (those undergoing sham operation without vessel ligation and those undergoing no operation) there was a rise in protein in the aqueous of the uninjured eye. In the rabbits with the communicating artery transected, no such rise in contralateral aqueous protein occurred. It is concluded that in the rabbit this vascular connection can explain the contralateral hyperemia and aqueous protein increase seen after monocular trauma.