The present invention relates to novel morpholin-acetamide compounds of formula (I) useful for the treatment of inflammatory diseases. Compounds of formula (I) ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, X, a, b and Z are as defined in the specification, processes for preparing them, formulations containing them and their use in therapy for the treatment of inflammatory diseases.