A process for isolating lactoferrin from milk or a casein-containing component or product containing lactoferrin, comprising subjecting a precipitate of casein obtained from the milk of the casein-containing component or product, with which precipitate at least part of the milk lactoferrin is associated, to a treatment with an extraction medium whereby at least part of the lactoferrin associated with the precipitate of casein is released to the medium. When lactoferrin has been released, the medium may be subjected to different types of purification operation steps. The purification operations are selected in accordance with the purity requirements of the intended specific application. Furthermore, lactoferrin and/or a composition comprising lactoferrin according to the above-mentioned process is provided.