Renal ischemia is of great clinical interest because of its role in renal failure and renal graft rejection. The purpose of this study was to investi­gate the possible protective effect of leflunomide against ischemia/ reperlusion (I/R) injury in the rat. Methods: Three groups of Sprague-Dawley rats (10 rats each), the con­trol group, I/R group and the lefluno­mide - treated I/R group. A renal I/R injury was induced by a left renal ped­icle occlusion to induce ischemia for 45 min, followed by 60 mins of reper-fusion with contralateral nephrectomy In rats. The rats in Leflunomide treat­ed l/R group were pretreated intra-gastrically with a leflunomide suspen­sion (10 mg/kg) 60 min before the ischemia induction. Thio barbituric acid reactive substances (TEARS),
nitric oxide (NO), tumor necrosis fac­tor alpha (TNF-ct), catalase (CAT) su-peroxide dismutase (SOD) activities were determined in renal tissue, while, creatinine, blood urea nitrogen (BUN) were measured in blood. Re­sults: Our results indicate that TBARS, NO, TNF-a, BUN and creati­nine levels, were significantly higher in the I/R group than those in the con­trol group. Leflunomide administration significantly decreased these parame­ters. SOD and CAT activities signifi­cantly decreased after I/R injury when compared to the control group. Leflu­nomide treatment significantly in­creased activities of these enzymes when compared to the I/R group.