To determine the incidence of infectious endophthalmitis in the early postoperative period following penetrating keratoplasty, and the type and origin of the causative organisms, all cases of penetrating keratoplasty performed at the Emory University affiliated hospitals between January 1977 and March 1982 were reviewed. Four (0.2%) of the 1,876 cases developed infectious endophthalmitis. In all four, evidence of infection developed within 72 hours, and in three the donor rim culture grew the same organism as was obtained from the anterior chamber or vitreous. The causative organisms were Streptococcus pneumoniae, Staphylococcus aureus, group D Streptococcus-enterococcus, and Pseudomonas aeruginosa. Eyes with positive donor rim cultures had a 22-fold increased incidence of endophthalmitis.