The incidence of transplanted kidneys derived from elderly donors is increasing because of the larger waiting lists and greater age of patients with end-stage renal failure. Compared with young donors, one of the problems is the heightened risk of neoplasm transmission. We report 2 cases of kidney recipients, both of whom developed a sarcomatoid renal cell carcinoma after receiving a kidney transplant from the same 68-year-old male donor, who did not show signs of a neoplasm on a previous abdominal ultrasound or a pretransplant biopsy. The first recipient was a 66-year-old woman who developed a kidney mass with several urologic obstructive complications, tumor dissemination, and death at 9 months after kidney transplantation. The second recipient was a 48-year-old asymptomatic man with normal renal function, who was studied after the results of the first recipient, revealing another renal tumor. Transplant nephrectomy was performed and a peritoneal implant was resected. The patient is alive without evidence of a neoplasm after 18 months. Herein we have discussed the mechanisms of neoplasm transmission in kidney transplantation and possible strategies for its prevention and treatment.