This international standard specifies a qualitative and quantitative testing method to determine the content of wool, cashmere, yak and their blends in textiles by: microscope preliminary screening, protein extraction, enzymatic digestion and specific peptides detection using liquid chromatography-mass spectrometry. This method can be applied to relevant textile products at each process stage (i.e. from raw material to garment). It can be applied to different types of textile materials (e.g. staples, tops, yarns and fabrics) that contain wool, cashmere or yak. A homogeneous distribution of the components in the sample is required. The method is based on a preliminary identification of all fibres in the blend on the basis of their morphology, by light microscopy. Then the protein are extracted by Thiourea/Urea/DTT solution. An enzymatic digestion by Trypsin of the protein extracted from the fibres is carried out. Analysis of the oligopeptidic ratio is performed by LC-MS and the percent composition is calculated [1,2].