We encountered two cases of macular infarction that occurred after vitrectomy performed for mild endophthalmitis, which, on culture, yielded Staphylococcus epidermidis. At the end of each vitrectomy, 0.4 mg of gentamicin, 1.0 mg of cefazolin, and 0.32 mg of dexamethasone were injected into the vitreous cavity. We are concerned that the macular lesion was a retinal toxic effect of gentamicin because of the recent description of similar lesions occurring after the inadvertent intraocular injection of massive doses of this drug.