A method for inactivating xenoantigens in biological tissues, particularly in tissues that can be used to manufacture bioprosthetic substitutes and/or in bioprosthetic substitutes that are already prepared and intended for human or veterinary clinical use. Such method entails the following steps: - providing a solution based on phenolic compounds, polyphenolic compounds or derivatives thereof, for the inactivation of at least part of the xenogeneic epitopes from such tissues; - incubating the samples to be treated in the various solutions based on phenols/polyphenols in controlled conditions; - subjecting the treated tissues to a series of washes.