The prevention of oxidative degradation in fats and oils is largely controlled by the use of synthetic phenolic antioxidants. Antioxidants, BHA: 2-&-3-tert-butyl-4-hydroxyanisol, BHT: 3,5-di-tert-butyl-4-hydroxytoluene, TBHQ: tert-butylhydroquinone, PG: propyl gallate, PTG: pentyl gallate, OG:octyl gallate, were extracted from fatty foods with hexane and from hexane layer to presaturated acetonitrile with hexane. The polar phenolic hydroxyl groups of antioxidants were silylated with MSTFA and injected to Gas Chromatography/Mass Spectrometry. The calibration plots were linear in the investigated range, 0.1~10.0 $mu extrm{g}$/g. The limit of detection for 6 phenolic antioxidants was 0.1 $mu extrm{g}$/g. Recoveries and reproducibilities from samples fortified at 1.0 $mu extrm{g}$/g were in the range of 70~90% and 0.5~13%, respectively. The simultaneous determination of phenolic antioxidants in fatty foods using GC/MS-SIM mode and macro program was described.