Pyrrolealdehydes of the formula I ##STR1## wherein R and R.sup.1 independently of one another denote hydrogen or alkyl with 1 to 4 C atoms, R.sup.2 denotes alkyl, which is substituted by acylamino of the formula II ##STR2## wherein X stands for an oxygen or sulphur atom and R.sup.3 denotes hydrogen, optionally substituted alkyl or alkylamino, cycloalkyl with 5 to 7 C atoms, optionally substituted phenyl, an amino group or an optionally substituted phenylamio group, and pharmaceutically acceptable acid addition salts thereof, and wherein R.sup.3 cannot represent hydrogen if R and R.sup.1 denote hydrogen and the pyrrole ring is formylated in the 3-position, their preparation and their use.