The invention relates to a method for extracting a protein from milk, having at least one hydrophobic pocket and a negative charge to the natural pH of milk, that comprises the following steps: a) skimming and delipidation of the milk b) passing the delipidated and skimmed fraction containing the protein on a chromatographic substrate on which is grafted a ligand having both a hydrophobic characteristic and an ionic characteristic in pH conditions enabling the protein to be retained on the substrate, the pH being higher than 4.6 c) elution of the protein d) purification of the eluted fraction by removing the milk proteins from the eluted fraction and e) recovering the protein.
