The effect of 35 minutes of warm ischemia (37C) on renal function and adenine nucleotide content of canine kidneys preserved for 24 and 48 hours in Euro-Collins (EC) solution was investigated. In addition, the effect of donor pretreatment with intravenous mannitol, furosemide and methylprednisolone and the addition of adenosine triphosphate (ATP/MgCl2) to the EC flush and storage solution was studied. Donor pretreatment or the addition of ATP/MgCl2 to the flushing and storage solution did not significantly affect postautotransplant renal function of kidneys stored for 24 hours, although it improved tissue adenine nucleotide levels. Results after 48-hour preservation were significantly poorer. These experiments demonstrate that canine kidneys subjected to 35 minutes of warm ischemia time can be stored for 24 hours in EC solution and thereafter provide immediate life-sustaining function.