Aryl ethanol-hydroxylamines of the formula ##STR1## in which Ar represents aryl or heteroaryl, each of which can optionally be substituted, andR represents alkyl, aryl, aralkyl, heteroaryl, heteroaralkyl or cycloalkyl, each of which can optionally be substituted,or physiologically tolerated salts thereof, exhibit animal growth-promoting properties. Intermediates therefor of the formula ##STR2## with the exception of phenyl and p-bromophenyl, are also new.