BACKGROUND Even with recent data, 5-10% of pancreas transplants experience early technical failure. Graft thrombosis is the primary cause of early technical failure, even when only optimal grafts are used, as is the case in Korea. The purpose of this study was to determine whether we can avoid thrombotic graft failure by modifying venous outflow. MATERIAL AND METHODS Between March 2017 and December 2021, a total of 59 pancreas transplantations were performed. Until May 2019, 31 cases of fence-angioplasty with cadaveric vena cava were performed to graft portal veins (the vena cava group). Since then, a total of 28 aortic interposition grafts have been performed to graft portal veins (the aortic group). RESULTS Between the 2 groups, there was no significant difference in baseline characteristics. Each group had 1 instance of technical failure. Early graft failure rates were 3.2% and 3.4%, respectively (P=1.000), while 1-year graft survival rates were 96.8% and 94.4%, respectively (P=0.991). Although a graft-threatening thrombosis occurred in the vena cava group, neither group experienced thrombotic graft failure, despite the decreased (vena cava group) or absence of heparin use (aorta group). CONCLUSIONS When the optimal graft is used, both techniques of modifying venous outflow can significantly reduce thrombotic graft failure.