Purpose: The incidence of diarrhea after renal transplant is common, varying from 13-64%, depending on the immunosupressant regime. Post-transplant diarrhea doubles the risk of renal graft loss and mortality. Studies of liver transplant cohorts have suggested that the most common causes of post-transplant diarrhea are Clostridium difficile, cytomegalovirus, and the use of immnosupressive regimes, including mycophenolate mofetil, cyclosporine, tacrolimus, and sirolimus. Recently, norovirus has been implicated as a cause of chronic diarrhea post-renal transplant. Norovirus is the most common cause of acute gastroenteritis worldwide. In immunocompetent individuals, it is self-limiting. A literature review found two case series of patients (n=9 and n=15) demonstrating persistent norovirus infection following renal transplant. Other cases have been documented in immunosupressed patients. In our center, we have identified two cases of chronic diarrhea in renal transplant recipients caused by chronic Norovirus infection. The first was a 65 year-old male with a two-year history of diarrhea following an episode of acute gastroenteritis. Stool frequency was 3-6 bowel movements per day. Stool studies and tests for C. difficile were negative, but tested positive for norovirus. A colonoscopy was normal. Norovirus PCR was performed three times during the course of the diarrhea, and was positive each time, remaining positive for over 16 months. The second patient was a 67-year-old female with an 18-month history of chronic diarrhea following a severe self-limited gastroenteritis. She presented with 5-6 bowel movements a day, and scant blood on a few occasions. Again, colonoscopy and stool studies were normal, as were multiple tests for C. difficile. Norovirus PCR was positive throughout the course of her illness -- in this case for a duration of over 15 months. While diarrhea is common after kidney transplantation, we present two cases of chronic diarrhea post-renal transplant with persistently positive Norovirus PCR. Norovirus may persist in renal transplant recipients or immunocompromised individuals, and should be considered when these patients present with chronic diarrhea.