The objective of the present study was to evaluate the recently proposed aerobic machine preservation with the noncolloidal HTK solution by comparison with the colloidal Belzer machine perfusion solution (MPS) after procurement of marginal kidneys from non-heart-beating donors. Kidneys were harvested 40 minutes after cardiac arrest in German Landrace pigs and subjected to 18 hours of oxygenated hypothermic machine perfusion with either Belzer MPS or modified HTK via the renal artery (Psys < 40 mm Hg). During machine perfusion transrenal flow was approximatively twofold higher and calculated oxygen uptake was increased by 30% using the colloidal Belzer MPS, but overall enzyme release was comparable in both groups. After heterotopic transpantation with bilateral nephrectomy of the recipient, there were no differences with respect to initial tissue perfusion in vivo (evaluated by laser Doppler flowmetry) as well as urine production and median serum levels of urea or creatinine over 1 week of follow-up between grafts perfused with HTK or Belzer MPS. In conclusion, provision of oxygen during storage is possible by low-flow perfusion with HTK as with Belzer MPS.