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Background and Objectives: Ischemia reperfusion (IR) occurs when the blood supply returns to the tissue after a period of ischemia, or lack of oxygen it is a common cause of acute renal failure. The present study evaluated the effect of pretreatment with omega 3 fatty acids on ischemia reperfusion injury. Materials and Methods: Right nephrectomy was performed on 81 male Wistar rats (255-300 g). The rats received either omega 3 fatty acids (DHA+EPA 200 mg/kg/d) or distilled water orally for 14 d prior to ischemia reperfusion (6, 24, 48 h reperfusion). Serum creatinine (SCr), BUN, creatinine clearance (CCr), and fractional excretion of sodium (FENa) were measured. Superoxide dismutase (SOD) and catalase (CAT) activities and renal histological injury were also determined. Results: SCr, BUN and FENa increased after 6-48 h of reperfusion (p < 0.01). CAT and SOD activity decreased (p < 0.05) in the IR group. DHA+EPA decreased SCr, BUN and FENa, (p < 0.05 vs. IR) and increased CCr, CAT, and SOD activity (p < 0.05 vs. IR) for 6-48 h after ischemia. IR induced mild (6 h, p < 0.05) to severe (24-48 h, p < 0.01) tissue damage. The tissue damage decreased significantly for the DHA+EPA group over the IR group (p < 0.05 vs. IR 24-48 h). Conclusion: The results suggest that pre-ischemic exposure to DHA+EPA ameliorates oxidative stress and could improve kidney function by decreasing SCr, BUN, and FENa, and increasing CCr . Keywords: Omega 3 fatty acids (DHA+EPA), Ischemia reperfusion, Oxidative stress, Acute renal failure