The present invention relates to novel imidazolidine derivatives of formula I, ##STR1## wherein A, E, Z, R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 have the meanings indicated in the claims. The compounds of formula I are valuable pharmaceutical active compounds which are suitable, for example, for the treatment of inflammatory diseases, including rheumatoid arthritis, or allergic diseases. The compounds of formula I are inhibitors of the adhesion and migration of leukocytes and/or antagonists of the adhesion receptor VLA-4 belonging to the integrins group. They are generally suitable for the treatment of diseases which are caused by an undesired extent of leukocyte adhesion and/or leukocyte migration or are associated therewith or in which cell-cell or cell-matrix interactions which are based on the interactions of VLA-4 receptors with their ligands play a role. The invention furthermore relates to processes for the preparation of the compounds of formula I, their use and pharmaceutical preparations which contain compounds of formula I.