Approximately 10000 deceased donor organs are available yearly for 85 000 US patients awaiting kidney transplant. Living kidney donation is essential to close this gap and offers better survival rates. However, nationally, 80% of potential donors evaluated fail to donate. Nurse coordinators who perform predonation screening and education need additional insight into the large number of potential donors who fail to complete the donation process. Reasons for nondonation in donor candidates undergoing medical evaluation, and variables affecting nondonation at Vanderbilt University Medical Center between 2004 and 2009 are examined. Multivariable logistic regression models are used to test the effects of age and race on donation status and reasons for nondonation. Summary data are frequencies, percentages, and means (SD). The sample included 706 candidates (63% female, 80% white; mean age, 40 [SD, 12] years). Almost half (46%) received clearance to donate. Undiagnosed hypertension (14%), abnormal glucose tolerance (10%), and protein-urea (9%) were the most prevalent medical reasons for nondonation. About 13% of candidates changed their minds during evaluation. Analyses demonstrated an increased likelihood of older candidates (P < .001) and a decreased likelihood of white candidates (P = .007) being excluded from donation. Within the nondonation group, increased age was associated with undiagnosed hypertension and abnormal glucose tolerance (both race-adjusted, P = .01). Younger candidates (race-adjusted, P = .003) and African Americans (age-adjusted, P = .04) were more likely to decide against donation. The most prevalent medical reasons for nondonation could be identified through enhanced prescreening, and improved preevaluation education could decrease nondonation rates.