This International Standard specifies a routine gas liquid chromatographic method for the determination of the sterol composition in anhydrous milk fat extracted from dairy products directly on the unsaponifiable matter, without purification and derivatization. The first goal of this International Standard is the quantitative evaluation of cholesterol, which represents about 98 % of the sterol fraction of pure milk fat. Moreover, in the case of analysis of milk fat in a mixture of vegetable fats, the specified procedure allows the evaluation of the most important phytosterols. The procedure has been validated on milk fat samples containing approximately 28 % to 32 % of vegetable fat. Due to the absence of the purification step, which allows the complete removal of interfering compounds from the unsaponifiable matter, particular care should be taken when applying this method to the verification of the purity of milk fat of unknown origin. In the case of suspicious results, the reference method described in ISO 12078|IDF 159 can be used.