Mechanical properties and morphologies of nylon 11/ethylene-octene copolymer blends have been investigated. The ethylene-octene copolymer (POE) employed in this study was grafted with maleic anhydride (MAH) and thus has the potential to react with the amine group of nylon 11. Nylon 11/POE-g-MAH and nylon 11/POE/POE-g-MAH blends with varying MAH graft ratios were prepared. In this paper, the effect of MAH graft ratio on ductile-brittle transition temperature (DBTT), mechanical properties, and morphology of blends was studied. The results showed that incorporation of POE-g-MAH could remarkably improve the compatibility between the nylon and POE elastomers, thus increasing the toughness of the resultant blends. The compatibilizing effect on impact strength became more pronounced with increasing MAH graft ratio. DBTTs of blends were initially lowered dramatically with the increasing maleic anhydride graft ratio, but over 0.56% MAH content, DBTTs of blends did not drop further, while tensile strength and tensile modulus dropped slightly because of the decreased glass transition temperature (Tg) of nylon 11/POE blends, resulting from the increased compatibility between the two phases. The role of MAH graft ratio on the POE particle size and dispersion of POE on nylon 11 matrix was also studied.