Heterocyclic substituted 2-acylamino-5-thiazoles, their preparation and pharmaceutical compositions containing them.A 2-Acylaminothiazole of formula: ##STR1## in which R.sub.1 is H, an alkyl or a substituted alkyl; R.sub.IV is a cycloalkyl, an aromatic group such as phenyl or a heterocyclic group which are unsubstituted or substituted; R.sub.V is a substituted alkyl, a substituted carboxy such as an ester or an amide; or R.sub.IV and R.sub.V together represent a phenoxyalkylene group which may be substituted on the phenyl; and Z is a heterocyclic e.g. indolyl group; or a salt of compound (I).