The present invention relates to tetrahydronaphthyridine derivatives of the general formula (I): ##STR00001## or of the general formula (I') ##STR00002## in which A and R.sup.1 are as defined within, and to processes for the preparation of, intermediates used in the preparation of, compositions containing and the uses of, including the treatment diseases mediated by H3 ligands, in particular inflammatory, allergic and respiratory diseases, disorders and conditions.