Background Due to the increasing number of renal transplantations, elective and emergency surgery in transplanted patients is becoming a relevant challenge in clinical routine. The current data on complication rates of renal transplant recipients, which must undergo another surgical procedure not connected with transplantation, is inhomogeneous. The rate of anastomotic leakage and wound infection appears to be increased in these patients. Perioperative acute kidney injury or even graft failure with need of dialysis might occur after surgery. Therefore, the indication for surgery has to be examined more than critically. The aim of this study was to analyze morbidity and mortality of renal transplant recipients after abdominal surgery for graft-unrelated surgical conditions. Method We performed a monocentric and retrospective observational study in the surgical critical care unit of the Department of Surgery at the Medical Center of the University of Freiburg, Germany. Clinical data was collected from all patients after kidney transplantation from 2005 to 2015, which had to undergo elective or emergency abdominal surgery for transplant-unrelated surgical problems. Results The overall postoperative hospital mortality of the renal transplant recipients was 21% with sepsis and multiple organ failure due to infectious complications being the major causes of death. Anastomotic leakage was the most common surgical complication followed by surgical site infection. The need of reoperation in this group of patients was 38% mainly due to anastomotic leakage and postoperative hemorrhage. Postoperative renal graft failure with need of dialysis was seen in 11% of our patients. Conclusions Kidney transplant recipient undergoing elective or emergency abdominal surgery not related to transplantation have worse postoperative outcomes. The overall mortality is high, mainly due to infectious complications and anastomotic leakage.