We investigated the effects of allopurinol on renal damage following renal ischemia. Male Wistar rats weighing 250-300 g were classified into enflurane and allopurinol groups and anesthetized for 5 minutes using 1.7 MAC of enflurane in 30% oxygen. Then the left renal artery was dissected and clamped. Arterial occlusion was performed under 1.3 MAC enflurane for 30 minutes. Anesthesia was maintained for an additional 90 minutes after releasing the clip. In the allopurinol group, the rats were administered with allopurinol 3 mg.kg-1 intravenously prior to renal ischemia. At the end of anesthesia and 24 hours after the discontinuation of anesthesia, the necrotic areas, kidney weight/body weight ratios, gamma-GTP and NAG activities of the kidney which had been clamped were examined. Urinary gamma-GTP and NAG activities and serum inorganic fluoride concentrations were also measured. The necrotic area was significantly smaller in the allopurinol group than in the enflurane group. The activity of gamma-GTP in the kidney was higher in the allopurinol group than in the enflurane group. The kidney weight/body weight ratio was lower in the allopurinol group than in the enflurane group. There was no difference in serum inorganic fluoride concentration between the allopurinol and enflurane groups. These results suggest that allopurinol decreases renal damage following renal ischemia under enflurane anesthesia.