A flame resistant thermoplastic resin composition having improved impact resistance and chemical resistance is provided. The flame resistant thermoplastic resin composition includes about 100 parts by weight of a base resin; about 3 to about 20 parts by weight of a halogen-containing flame retardant (C); and about 0.1 to about 6 parts by weight of an antimony-containing flame retarding aid (D). The base resin includes about 20 to about 99% by weight of an epoxy group-containing rubber modified aromatic vinyl based resin (A) comprising about 1 to about 99% by weight of an epoxy-containing rubber modified aromatic vinyl based copolymer (Al), about 1 to about 99% by weight of an epoxy-containing vinyl copolymer (A2), and about 0 to about 98% by weight of an aromatic vinyl based copolymer (A3), and about 1 to about 80% by weight of a polyester resin (B).