A tetrafunctional epoxy monomer, N,N,N*-N*-tetraglycidyl-4,4*-diaminodi- phenyl methane (TGDDM), has demonstrated to be a highly efficient reactive compati- bilizer in compatibilizing the immiscible and incompatible polymer blends of polyamide- 6 (PA6) and poly(2,6-dimethyl-1,4-phenylene ether) (PPE). This epoxy coupler can react with both PA6 and PPE to form various PA6-co-TGDDM-co-PPE mixed copoly- mers. These interfacially formed PA6-co-TGDDM-co-PPE copolymers tend to anchor along the interface to reduce the interfacial tension and result in finer phase domains and enhanced interfacial adhesion. A simple one-step melt blending has demonstrated to be more efficient in producing a better compatibilized PA6/PPE blend than a two- step sequential blending. The mechanical property improvement of the compatibilized blend over the uncompatibilized counterpart is very drastic, by considering the addition of a very small amount, a few fractions of 1%, of this epoxy coupling agent. q 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1805-1819, 1998