Unfortunately, pancreas transplantation (PTx) has been associated with the highest surgical complication rate of all the routinely performed organ transplant procedures. Complications can arise not only from the pancreas itself but also from the simultaneously transplanted duodenum. One of these complications is gastrointestinal bleeding, which might be from anastamotic site ulcer, pseudoaneurysm, arterioenteric fistula, severe rejection, or cytomegalovirus infection. In this case series, we present three patients presented with severe anemia 3 to 6 months after PTx with enteric drainage by end-to-end anastomosis of ascending loop of a Roux-en-Y to donor duodenal C-loop. The source of bleeding in all three cases was non-marginal donor duodenal C-loop ulcers. High donor pancreas exocrine output associated with relatively low drainage of a small end-to-end anastomosis may be the cause of these ulcers. It is recommended to use a side-to side anastomosis to prevent this complication
