Nanocomposites of polyamide 6, acrylonitrile-ethylene-propylene-diene-styrene and organically modified montmorillonite compatibilized with methyl methacrylate-co-maleic anhydride (PA6/AES/OMMT/MMA-MA) (63/27/5/5wt%) were prepared by melt blending process in a single extrusion step. The effects of different OMMT surfactants on structural and mechanical properties of the nanocomposites were evaluate. Transmission electron microscopy (TEM) and wide-angle x-ray diffraction (WAXD) analysis revealed intercalated structures for both compositions prepared with a non-surface modified and a nonpolar MMT; in contrast, a polar organoclay led to an exfoliated structure. Small angle x-ray scattering (SAXS) patterns suggest that PA6 crystallization process can be hardly affected by the different organo-modifiers once disparities on the long period and crystalline lamellae thickness were clearly observed among the compositions. As expected, the polar OMMT exhibits good interaction with PA6 matrix and to the detriment of toughness resulted in a reinforcement effect of the nanocomposites. However, the nonpolar OMMT surprisingly exhibited the best balance between toughness and stiffness. It is hypothesized that the nonpolar OMMT should be preferentially located on PA6/AES interface and, even in an intercalated structure, might favor the compatibilization process for this composition. Key-words: polymers, nanocomposites, surfactant, crystallization, organoclay.