We performed a retrospective analysis of 291 consecutive scleral rim cultures, taken at the time of corneal transplantation, from 1981 to 1986. There were 82 positive cultures (39%), and the most common pathogen was Staphylococcus epidermidis, with 24 positive cultures (30%). Ten of these (42%) were resistant to gentamycin. There were no cases of endophthalmitis or other infections in the immediate postoperative period. We also found 15 positive cultures of Streptococcus viridans. Of these, 13 (87%) were resistant to gentamycin but sensitive to most other antibiotics. Even though endophthalmitis is rare following penetrating keratoplasty, the emergence of resistant strains of Streptococcus viridans and Staphylococcus epidermidis suggests that eyebanks need to consider the addition of a second antibiotic to their MK medium.