Based on previous data, this research deals with the study of cellular ultrastructure of renal tissue (cortical and medullary) in conditions of preservation through a continuous hypothermic pulsatile perfusion, using a solution that substitutes plasma as the perfusate. This experiment was done on isolated dog kidneys perfused with a specialized perfusion machine. The results clearly show that with this method of renal preservation, no major lesions or irreversible modifications of the nephrons occur within 12 hours, offering the organ posttransplanting compatibility.