Abstract: In the method for combining with liposomes heterogeneous substances contained in a mixture, in particular, allergenic substances such as allergens and/or allergenic extracts, contained in an allergenic preparation, by adsorption on the surface of, and/or incorporation in, liposomes which comprise cholesterol, a phospholipid and/or at least one ionic lipid which gives the liposome a positive or negative charge, the liposome or its constituents are combined with the mixture of heterogeneous substances, the pH of the entire combination being higher or lower than the isoelectric point ip of the substances contained in the mixture, depending on whether the ionic lipid is charged positively or negatively respectively.