The mechanical properties of polystyrene/polyamide-6 (50/50 wt/wt) blends were improved by additions of small amounts of poly(styrene-g-ethylene oxide) (SEO) during compounding by extrusion. Tensile testing of injection-molded samples revealed that the blends developed a yield point after addition of 1 wt % SEO. The elongation at break increased by almost a factor of 6, and the impact strength increased by a factor of 1.5 after adding 3 wt % SEO. Morphological analysis by electron microscopy showed that additions of SEO resulted in decreased domain sizes, and seemed to promote interfacial adhesion. The morphologies of the compatibilized blends also had a higher degree of anisotropy, as compared with the uncompatibilized blend.