Nanoparticles are applied in polymer matrices because of building up an inorganic network within an organic network resulting in a simultaneous increase of stiffness and toughness provided that a good degree of dispersion with a very low amount of agglomerates can be realized. To prevent these kinds of agglomerates, the incorporation of appropriate nanoparticle dispersions is promising. Using nanoparticle containing dispersions, we can produce nanocomposites via a direct injection molding process with excellent nanoparticle dispersion in the resulting nanocomposite. TiO2- (15 nm and 300 nm) and Al2O3- (13 nm) particle containing dispersions were manufactured and incorporated in polyamide 6 (PA6) via the addition of a nanoparticle containing dispersion within an injection molding process (IM). Agglomeration has to be suppressed during injection molding process and the nanoparticles have to cross over from the dispersing agent to the polymer matrix melt in which they have to be well distributed. The resulting mechanical (tensile and Charpy impact) and morphological (SEM and TEM) properties of those nanocomposites are discussed. The impact toughness and Young's modulus could be enhanced with slightly decreasing tensile strength. The nanoparticles could be well distributed in the polymer matrix. The achievable distribution quality is equal to the distribution achieved in a melt kneading process. Thus, materials with enhanced elongation at break with a very good dispersion quality were produced in a single production process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40641.