The present invention relates to an aqueous polyurethane-polyurea dispersion (PD) having polyurethane-polyurea particles, present in the dispersion, having an average particle size of 40 to 2000 nm, and having a gel fraction of at least 50%, obtainable by(I) preparing a composition (Z) comprising, based in each case on the total amount of the composition (Z),(Z.1) 15 to 65 wt % of at least one intermediate containing isocyanate groups and having blocked primary amino groups, its preparation comprising the reaction (Z.1.1) of at least one polyurethane prepolymer containing isocyanate groups and comprising anionic groups and/or groups which can be converted into anionic groups, with (Z.1.2) at least one polyamine comprising at least two blocked primary amino groups and at least one free secondary amino group, by addition reaction of isocyanate groups from (Z.1.1) with free secondary amino groups from (Z.1.2), (Z.2) 35 to 85 wt % of at least one organic solvent which possesses a solubility in water of not more than 38 wt % at a temperature of 20° C.,(II) dispersing the composition (Z) in aqueous phase, and(III) at least partly removing the at least one organic solvent (Z.2) from the dispersion obtained in (II).The present invention also relates to basecoat materials comprising the dispersion (PD), and to multicoat paint systems produced using the basecoat materials.