Palm oil has been widely used in Indonesia as cooking oil. Repeated heating at high temperatures will damage the cooking oils by the formation of peroxide, aldehyde, ketone, alcohol, and hydrocarbon compound. Previous studies reported that giving cooked and oxidized cooking oils to livestocks has resulted in various poisonous phenomena. To examine liver damage caused by using cooked palm oil, 36 male Balb/c mice are divided randomly into 6 groups (n = 6), and to each group were administered orally: (1) water, (2) fresh palm oil, (3) 4 times cooked palm oil, (4) 10 times cooked palm oil, (5) 20 times cooked palm oil, and (6) 40 times cooked palm oil; using gavage needle at a dose of 0,5 ml/100 g body weight/day, once a day for 7 successive days. On the eighth day, part of the liver of each mouse was examined histologically, stained using Hematoxylin-Eosin to count the number of necrotic hepatocytes in 20 centrilobular regions randomly. The number of neutrophils stained using Naphthol AS-D chloroacetate esterase were also counted in 20 centrilobular regions randomly. The other part of the liver was homogenized to determine the concentration of malondialdehyde (MDA) using TBARS method. The results show a significant increased (p<0,05) in the number of necrotic hepatocytes, the number of neutrophils, and the concentration of MDA of the groups treated with 10, 20, and 40 times cooked palm oil compared with the group treated with fresh palm oil. Further studies about the toxicology of cooked palm oils are warranted to elucidate the biomolecular basis underlying the xenobiotic metabolism and the defence mechanisms of the liver.