Hydrogenated nitrile rubber (HNBR) and synthetic nanofillers, viz. water-swellable sodium fluorohectorite (FH) and water dispersible boehmite alumina (BA), were used to toughen and reinforce polyamide-6 (PA-6). FH and BA were introduced in HNBR latex that was dried prior to melt mixing with PA-6. Binary blend (PA-6/HNBR) and ternary nanocomposites (PA-6/HNBR/nanofiller) were produced and their structure-property relationships studied. HNBR was coarsely and microscale dispersed in PA-6. FH, slightly intercalated, was present in PA-6 and in the PA-6/HNBR interphase, whereas BA was mostly located in the HNBR droplets. HNBR improved the ductility of the PA-6/HNBR blend at cost of stiffness and strength. The fracture toughness and energy, determined on notched Charpy specimens at different temperatures (T = -30 degrees C, room temperature, and T = 80 degrees C) were improved by blending with HNBR at 9 wt %. Additional incorporation of the nanofillers in 2.5 wt % enhanced the stiffness and strength of the PA-6/HNBR blend but reduced its ductility. The fracture toughness of the ternary nanocomposites was between those of PA-6 and PA-6/HNBR, whereas their fracture energy fairly agreed with that of the parent PA-6. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 897-902, 2012