Background. The impact of cytomegalovirus in living related kidney transplantation remains controversial. This study considers the implications of donor and recipient cytomegalovirus (CMV) serology for the selection of living related donor. Methods. Graft survival was estimated by using the bivariate Kaplan-Meier method and multivariate Cox proportional hazards analysis for 7659 living related first transplantations performed in the United States between 1989 and 1994. The effects of donor CMV serology were estimated with respect to recipient CMV serology and compared with human leukocyte antigen (HLA) matching, transplantation, donor, and recipient characteristics. The implications of these estimates for the selection of living related donors were considered. Results. From Kaplan-Meier estimates, donor CMV-seropositive kidneys were associated with significantly reduced graft survival for CMV-seronegative recipients (p = 0. 0002) but not CMV- seropositive recipients (p = 0. 1623). These findings were verified by use of Cox proportional hazards analysis accounting for covariate factors. The impact of donor CMV-seropositive kidneys on CMV-seronegative recipients was similar to one HLA-DR match, greater than one HLA-B match, and significantly greater than one HLA-A match (p = 0.0331). Conclusions. Results identify donor CMV serology as an important determinant of transplantation outcome for living related first kidney transplant recipients who are themselves CMV seronegative. Consideration should be given to donor and recipient CMV serology when selecting an appropriate donor for living related kidney transplantation.