Low viscosity aqueous concentrates of betaine

Low-viscosity aqueous betaine surfactant concentrates with contents of solids ranging from approximately 50 to 60 wt % are obtained by condensing with halo acids and their salts fatty acid aminoamides in the presence of: a) viscosity regulators selected from the group comprising non-ionic surfactants having an HLB value ranging from 6 to 12 and/or hydroxycarboxylic acids; b) polyols; and optionally c) free fatty acids and their alkali salts.