Polyamide-6 (PA6)/montmorillonite (MMT) nanocomposites toughened with maleated styrene/ethylene butylene/styrene (SEBS-g-MA) were prepared via melt compounding. Before melt intercalation, MMT was treated with an organic surfactant agent. Tensile and impact tests revealed that the PA6/4% MMT nanocomposite fractured in a brittle mode. The effects of SEBS-g-MA addition on the static tensile and impact properties of PA6/4% MMT were investigated. The results showed that the SEBS-g-MA addition improved the tensile ductility and impact strength of the PA6/4% MMT nanocomposite at the expenses of its tensile strength and stiffness. Accordingly, elastomer toughening represents an attractive route to novel characteristics for brittle clay-reinforced polymer nanocomposites. The essential work of fracture (EWF) approach under impact drop-weight conditions was used to evaluate the impact fracture toughness of nanocomposites toughened with an elastomer. Impact EWF measurements indicated that the SEBS-g-MA addition increased the fracture toughness of the PA6/4% MMT nanocomposite. (C) 2005 Wiley Periodicals, Inc.