The invention provides lipid A mimics in which one or both of the sugar residues of a natural lipid A disaccharide backbone has been replaced with an aromatic group. These lipid A mimics may further differ from a natural lipid A molecule with respect to other structural characteristics, such as, a different number of phosphate groups present, changes in the number, structure and location of lipid chains and/or changes in the spacing and linkage of the sugar residues (or their aromatic replacements). The lipid A mimics may be lipid A agonists and as such may be useful as immunostimulatory agents in inducing or patenting an antibody and/or cell-mediated immune response, or may be lipid A antagonists and as such may be useful in treating or preventing a lipopolysaccharide (LPS)/lipid A-mediated disease or disorder. Also provided are methods for preparing the lipid A mimics.