2-benzimidazolinone compounds of the formula ##STR1## wherein R is lower alkyl,R.sub.1 and R.sub.2, which can be the same or different, are lower straight-chained or branched alkyl and one of R.sub.1 and R.sub.2 can also be hydrogen orR.sub.1 and R.sub.2 together represent an alkylene radical and R.sub.3 is hydrogen or acyl, i.e., alkanoyl or aromatic carboxylic acid moieties;and the pharmacologically acceptable salts thereof; have marked .beta.-receptor blocking action and are outstandingly useful in the treatment or prophylaxis of cardiac and circulatory diseases.