The conclusions drawn for the comparison of machine perfusion with cold storage depend on which trial data are used in the model. Owing to the lack of good research evidence that either ViaSpan or Soltran is better than the other, the cheaper, Soltran, may be preferable. In the absence of a cost-utility analysis, the results of our meta-analysis of the RCTs comparing ViaSpan with Celsior indicate that these cold storage solutions are equivalent. Further RCTs of comparators of interest to allow for appropriate analysis of subgroups and to determine whether either of the two machines under consideration produces better outcomes may be useful. In addition, research is required to: establish the strength and reliability of the presumed causal association between DGF and graft, and patient survival; investigate the utility impacts of renal replacement therapy; determine what the additional cost, survival and QALY impacts are of decreased or increased non-viable kidneys when discarded pre transplantation; and identify a reliable measure for predicting kidney viability from machine perfusion.