We report 4 cases of breast cancer transmission to transplant recipients from a single organ donor that occurred years after donation. The diagnosis of breast cancer was occult at the time of donation. All of the recipients developed a histologically similar type of breast cancer within 16 months to 6 years after transplantation. Three out of 4 recipients died as a result of widely metastasized disease. One of the recipients survived after transplant nephrectomy followed by cessation of immunosuppression and chemotherapy. This extraordinary case points out the often fatal consequences of donor-derived breast cancer and suggests that removal of the donor organ and restoration of immunity can induce complete remission.