The only shortcoming of PA6-based nanocomposites is low toughness, which is the same as that of the matrix. This work is focused on optimization of toughening these nanocomposites by introduction of small amounts of finely dispersed elastomers. A comparison of reactively compatibilized and analogous nonreactive elastomer-containing nanocomposites indicates the best-balanced mechanical behavior for polar nonreactive elastomers such as NBR and E-MA. This is explained by a significant compatibilizing effect of clay. Besides the elastomer particle size and its properties, the clay localization and its degree of ordering in the interfacial region also significantly influenced mechanical properties of the system. (c) 2006 Wiley Periodicals, Inc.