Samples of palm olein xvere irradiated xoith y -rays up to 12 kGy in the presence of oxygen. The extent of per oxidation was determined Iry peroxide value (PV), t hio barbituric acid (TBA) value and conjugated diene. Peroxide formation increased xoith increasing irradiation dose and changed rapidly during post-irradiation storage. After reaching maxima, during the first two days, the peroxide declined to relatively loxv values in both samples irradiated xoith 4 and 12 kGy. However, the TBA values of samples irradiated xoith loxo dose (4 kGy), xoere higher than that of samples irradiated with high dose (12 kGy), after four days storage. Peroxide formation occurred at 0°C but the yields were lower thaii that of room temperature. Concentration ofantioxidant (BHT) at 200ppm significantly inhibits per oxidation although it xoas partially destroyed by gamma-irradiation.