Aim Olive leaf (Olea europaea L.) extract (OLE) is a powerful anti‐oxidant rich in polyphenols. As oxidative stress plays an important role in aging, we investigated the effect of OLE on oxidative stress in the liver, heart and brain of aged rats. Methods Young (age 3 months) and aged (age 20 months) Wistar rats were used. Aged rats received OLE (500 and 1000 mg/kg/day) in drinking water for 2 months. Malondialdehyde (MDA), diene conjugate (DC), protein carbonyl (PC), glutathione (GSH), vitamin E and vitamin C levels, and superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px) and glutathione transferase (GST) activities were determined. Results MDA, DC and PC levels increased in tissues of aged rats. GSH levels decreased in the liver, but not in the heart and brain. There was no change of other anti‐oxidant parameters in tissues. Hepatic SOD and GSH‐Px protein expressions also remained unchanged. OLE treatment caused decreased tissue MDA, DC and PC levels, and increased hepatic GSH levels in aged rats. Other anti‐oxidant parameters, hepatic SOD and GSH‐Px protein expressions did not alter in aged rats by OLE treatment. Conclusion The present results suggest that OLE seems to be useful for decreasing oxidative stress in examined tissues by acting as an anti‐oxidant itself without affecting the anti‐oxidant system. Geriatr Gerontol Int 2014; ●●: ●●–●●.