Objective To evaluate the impact of portal or systemic venous pancreas graft drainage on patient and graft outcomes following simultaneous pancreas kidney transplantation (SPK). Methods We searched The Cochrane Library (2008, Issue 1), PubMed (1970 to Feb 2008) and EMBASE (1974 to Feb 2008) to find studies concerning the effect of systemic versus portal venous pancreas graft drainage on patient and graft outcomes. Meta-analyses were conducted using The Cochrane Collaboration’s RevMan 4.2 software. Results Three RCTs involving 401 simultaneous pancreas kidney transplants were included in our meta-analysis. Statistically significant differences were only observed in 3- and 5-year pancreas graft survival rates (P=0.03 and P=0.05). No significant difference was noted in patient or kidney graft survival rates. Conclusion Currently available evidences from RCTs does not support the effectiveness of portal drainage in preventing thrombosis, rejection or infection after SPK. Large-scale, long-term and appropriately designed RCTs are required to conclude whether portal and systemic drainage in pancreas transplantation are equivalent in terms of patient and graft survival.