Polyomavirus associated nephropathy is an increasingly recognized cause of allograft dysfunction and failure in kidney transplant recipients. Since June 30, 2004, the Organ Procurement and Transplantation Network/the United Network for Organ Sharing (OPTN/UNOS) has been collecting data on clinical polyomavirus (BK) disease (CPVD) using follow-up record. The aim of this study is to evaluate the impact of CPVD on graft survival after transplantation.