An alkenyl aromatic resin composition having an excellent impact strength, which comprises (I) 100 parts by weight of a rubber-modified alkenyl aromatic resin containing from 2 to 35 wt. % of conjugated diolefin components, or a resinous mixture containing at least a component of the resin thereof; and (II) 1 to 50 parts by weight of a random segment copolymer containing at least a Segment A which is a random copolymer of a conjugated diolefin and a vinyl-substituted aromatic compound with a weight ratio being ranging from 30:70 to 5:95 and at least a Segment B, which is a conjugated diolefin polymer or a random copolymer of a conjugated diolefin and a vinyl-substituted aromatic compound with a weight ratio being ranging from 100:0 to 75:25, the random segment copolymer being characterized by containing;(a) at least 10 wt. % of Segment A based on the total random segment copolymer,(b) at least 20 wt. % of Segment B based on the total random segment copolymer, and(c) at least 60 wt. % of a sum of Segment A and Segment B based on the total random segment copolymer.The resin composition of the present invention can be used to make a variety of useful products, such as film, foam, injection moldings and compression moldings.