This current study is designed as a cross-sectional study. A total number of 94 formalin-fixed paraffin embedded of renal cell carcinoma has been involved (55 males and 39 females, whose ages range from 18 to 80 years). Data have been collected from records of histopathological laboratories in Al-Sadder Teaching Hospital and some private histopathological laboratories in Najaf governorate during the period from December 2018 to May 2019 by using molecular technique (polymerase chain reaction) for detection of DNA for both BKPyV and JCPyV, and Immunohistochemistry technique (IHC) for detecting...