Considering the encouraging results recently reported on morphology refinement of immiscible polymer blends upon nanofiller addition, this work aims at investigating the effect of organo-modified Montmorillonite (OMMT) and carbon nanotubes (CNTs) on the morphology and resulting mechanical properties of polypropylene (PP) / polyamide (PA6) blends. Different types of OMMT (Cloisite 15A and 30B of low and high polarity respectively) were used to evaluate the influence of surfactant polarity on the blends properties. The results demonstrate that OMMT has a positive effect on the blends morphology, i.e. a decrease the dispersed phase size in an extent depending on the type of surfactant (polarity). Whatever surfactant polarity, OMMT platelets are localized in PA6 phase. Similar results were observed in the case of CNTs with decrease of dispersed phase size and selective localization of CNTs in PA6 phase. However, the analysis of mechanical properties of the different blends evidences a slight increase of stiffness but no or few improvement of deformation at break. This may be ascribed to the presence of nanofillers aggregates. Two different ways to improve the blends ductility were considered. First, optimization of processing by extrusion was undertaken. Powder polymers were used to avoid formation of aggregates in the feeding zone of the extruder. In addition, air cooling and direct injection-molding of the samples used for mechanical testing were implemented in order to avoid hydrolysis due to non-perfect drying of the blends. Thanks to this new approach, the ductility is significantly improved (500% increase of deformation at break) in the case of OMMT-based blends. In a second step, in the case of CNTs, a compatibilizer compatibilizer (maleic anhydride grafted PP, PPgMA) was combined with nanofillers. The ductility of the blends prepared this way also significantly increases and becomes still higher than the deformation at break achieved with the sole compatibilizer.