To investigate the risk of cytomegalovirus transmission by corneal transplantation, we quantitated anticytomegalovirus IgG levels of donor, preoperative, and postoperative serum samples. Of 118 patients, 79 (67%) were seropositive preoperatively. Twenty-five patients who were seronegative preoperatively received a graft from a positive donor and two (8%) seroconverted. Eleven patients who were seronegative preoperatively received a graft from a negative donor and one (9%) seroconverted. None of the patients who seroconverted had a febrile illness and all three grafts were clear.