A 72-year-old male with end-stage renal disease underwent a computed tomography scan to assess renal function. An oval-shaped mass, 50 mm × 60 mm in size, was discovered incidentally in his recto-vesical pouch. Because it was suspected to be a teratoma, which could be an impediment for future renal transplantation, surgery was performed. It revealed a giant peritoneal loose body, a rare entity, that has not been reported before in patients with renal chronic insufficiency.