Rabbit eyes in which vitrectomy was performed underwent three hours of hypothermic perfusion with either 22 C or 2 C lactated Ringer's solution. Clinical, electroretinographic, fluorescein angiographic, histologic, and ultrastructural examinations were performed. No changes were noted in eyes cooled with 22 C fluid. Reversible lens opacities, equivocal electroretinographic changes, and subclinical retinal detachments were found in the eyes cooled with 2 C fluid. Extreme cooling of eyes is not advisable, although temperatures of 22 C are well tolerated.