Abstract: An ethylenic thermoplastic resin composition suitable for a heavy duty bag which comprises(a) 20-80% by weight of an ethylene/.alpha.-olefin copolymer having a density of 0.910 to 0.940 g/cm.sup.3.(b) 70-5% by weight of a copolymer of ethylene and a carboxyl group containing monomer or a derivative thereof; and(c) 50-5% by weight of an ethylene/.alpha.-olefin copolymer having(i) a density in the range of not lower than 0.860 g/cm.sup.3 to lower than 0.910 g/cm.sup.3,(ii) a maximum peak temperature not lower than 100.degree. C. as measured according to differential scanning calorimetry (DSC) and(iii) a boiling n-hexane insolubles content not smaller than 10% by weight,provided the total amount of the components (a), (b) and (c) is 100% by weight.