Inosine, a purine nucleotide, has been used in 33 patients as a method of preventing ischaemic renal damage. The long-term results have been reviewed with a mean follow-up of 28 months. Inosine was administered either intra-arterially or intravenously. Renal function was assessed by serum creatinine, creatinine clearance and divided function renography. Inosine afforded satisfactory protection in ischaemic periods of up to 60 min, particularly if pre-operative function was normal. It was less reliable if pre-operative function was poor or in ischaemic periods greater than 60 min. Inosine is a helpful aid in ischaemic renal surgery.