The invention relates in particular to pseudodipeptides which are derived from functionalised aminoacids and which comprise fatty acid chains that are fixed on the amine functions of the pseudodipeptides in amide form, one of the ends of said pseudodipeptides having a functionalised auxiliary arm and the other end being a neutral or charged acid group. The inventive compounds have immunomodulatory properties when used as adjuvants. The inventive compounds can also be grafted onto an antigen in order to modulate the immune response or grafted onto a pharmacophore in order to improve its therapeutic action or its targeting. Finally, the inventive compounds can therefore be used in human and veterinary medicine as immunizing agents and as diagnostic tools.