A retrospective study of 36 cases of infectious keratitis in the graft following 885 consecutive penetrating keratoplasties was conducted to evaluate the spectrum of pathogens and the factors affecting graft survival. Gram positive cocci and gram negative rods were equally responsible (47% in both cases) for 94% of the infections. Epithelial defects were responsible for 64% of the ulcers; suture-related infections, for 36%. After the infectious keratitis resolved, only 50% of the patients had a clear graft. Because the visual prognosis is poor once infectious keratitis develops, aggressive treatment is essential as soon as any sign of infiltration appears.