The result of this study shows that a simple phosphate buffered sucrose solution (PBS) is better than hyperosmolar citrate (HOC) solution in the flush perfusion and hypothermic storage of canine kidneys for 72 hr prior to autotransplantation with immediate contralateral nephrectomy. The peroperative measurement of postre-perfusion renal blood flow revealed a significant reduction after 60 min in kidneys preserved with HOC solution. All grafts and animals in the PBS group (5/5) survived with primary renal function compared with one in the HOC group (1/5), which functioned after a period of oliguria. The early serum creatinine and urea levels were significantly lower in the PBS group, with a return to normal range within two weeks. This is reflected in higher inulin clearances and a more rapid recovery of proximal tubular function in the PBS animals, which also demonstrated a more rapid return of loop function and the ability to concentrate urine.