Effect of the egg yolky from laying hens intubated, p.o., astaxanthin (designated AEY) on the oxidation of mouse liver microtome was investigated using female ICR mouse (6~7 weeks of age). Mice were adapted in a temperature- and humidity-controlled house for one week and randomly divided into 7 treatment groups (10 mice/cage/treatment). Mice were intubated p.o., AEY (50, 100 and 150 mg) or control egg yolk (CEY, 150 mg) every week for 3 weeks. BHT (5 mg) and e -tocopherol (50 mg) were fed to mice as positive control. At week 4, the liver microsome was prepared from sacrificed mice. Protein content of mouse liver microsome with AEY treatment was relatively higher than that with CEY treatment. AEY treatment remarkably lowered the content of unsaturated fatty acids including oleic acid and linoleic acid, but raised that of the saturated fatty acids including stearic acid. AEY group showed relatively higher antioxidative activity than CEY, when used Asc/F $e^{+2}$ or NADPH/F $e^{+2}$ as oxidant. Antioxidative activity of AEY was more effective than $alpha$-tocopherol, but less effective than BHT.