Three patients with dense vitreous hemorrhages and nonrecordable bright-flash electroretinograms prior to vitrectomy all experienced great improvement in visual function and had recordable, though reduced-amplitude, electroretinograms soon after vitrectomy. None of the eyes had a major retinal detachment. The postoperative reduction in the electroretinogram in each case could be explained by the abnormality present. In common, the eyes required greater light than normal to elicit the electroretinograms post-operatively with clear media. While a damaged retina may have a nonrecordable electroretinogram in the presence of a preoperative dense vitreous hemorrhage, this may not preclude recovery of useful visual function following vitrectomy.