Betaine-amine oxides of the formula ##STR1## in which R denotes alkyl, alkenyl or hydroxyalkyl, each of which has 8-22 carbon atoms, R.sup.1 denotes hydrogen or methyl, R.sup.2 denotes ethylene, propylene or 2-hydroxypropylene, R.sup.3, R.sup.4 and R.sup.5 can be identical or different and denote C.sub.1 -C.sub.3 -alkyl or a group of the formula ##STR2## or R.sup.3 denotes a group of the formula --R.sup.2 --BR.sup.4 R.sup.5, X denotes a direct bond or a group of the formula--CO--,A and B denote a group of the formulae ##STR3## it being necessary for at least one amine oxide group and at least one betaine group to be present, a denotes 0 or 1, b denotes 1, 2 or 3, n denotes a number from 0 to 10 and m denotes 1, 2 or 3. These compounds are obtained by partially quaternizing the parent polyamines with the alkali metal salt of an .omega.-halogenocarboxylic acid and then oxidizing the non-quaternized nitrogen atoms. These betaine-amine oxides are suitable for use as surfactants in cleansing agents.