Over the last 2 decades, while kidney transplantation became the therapy of choice for end-stage renal disease, the increasing gap between the limited supply of cadaveric donors and the rising demand for kidneys led to the consideration of alternative strategies to provide more organs for transplant. The significant increase of mean donor age suggested the use of kidneys from older donors. In addition, an increasing number of donors with significant comorbidities (e.g., hypertension and diabetes) or deceased due to stroke have been used since the early 1990s, leading to the definition of the fuzzy and disputed concept of "marginal" donors. Such organs are eligible for organ donation but, because of extreme age and other clinical characteristics, are expected to produce allografts at risk for diminished posttransplant function. Thus, the challenge is now to improve the graft outcome gap between patients receiving grafts from "marginal" and "optimal" donors. This implies appropriate transplantation strategies during all transplant phases, including reduction of cold ischemia time, recipient selection, adaptation of immunosuppressive drug regimens, increase in nephron mass by dual kidney transplantation and improvement in the graft selection process using histological criteria. This review summarizes the current definition of a marginal donor and provides some suggestions for clinical management of these particular kidney transplants. We believe that in this particular transplanted population, an effective balance should be ensured between maintaining graft survival, reducing the impact of immunosuppressive toxicity and maximizing patient quality of life through the reduced incidence of cardiovascular disease and malignancies.