Disclosed herein is a flame retardant thermoplastic resin composition that has superior scratch resistance and mechanical properties, satisfying requirements for the appearance of housing materials resulting from a recent increase in volume of electrical and electronic products, and that contains a phosphorus-based flame-retarding agent, satisfying requirements for fire safety and prevention of environmental problems. The resin composition with scratch resistance comprises a base resin comprising (A) about 30 to about 90 parts by weight of a polycarbonate resin, (B) about 15 to about 50 parts by weight of a polymethylmethacrylate resin and (C) about 5 to about 50 parts by weight of a polyethylene terephthalate-based resin, and (D) about 5 to about 30 parts by weight of a phosphorus-based flame-retarding agent based on 100 parts by weight of the base resin. The composition may further comprise about 1 to about 30 parts by weight of an impact modifier based on 100 parts by weight of the base resin.