A flameproof thermoplastic resin composition is substantially free of phenolic resin, red phosphorous and silicone resin and comprises (A) about 40-95 parts by weight of a rubber modified styrene-containing resin comprising (a1) about 20-95% by weight of a styrene-containing graft copolymer resin containing about 19-50% by weight of acrylonitrile in the copolymer excluding rubber and (a2) about 5-80% by weight of a styrene-containing copolymer containing about 19-50% by weight of acrylonitrile; (B) about 5-60 parts by weight of a polyphenylene ether resin; (C) about 2-40 parts by weight of a compatabilizer comprising (c1) a styrene-containing copolymer containing about 5-18% by weight of acrylonitrile in the copolymer per 100 parts by weight of the sum of (A) and (B) or (c2) a styrene-containing graft copolymer having up to about 60% by weight of rubber wherein the compatabilizer contains about 5-18% by weight of acrylonitrile in the copolymer excluding rubber, per 100 parts by weight of the sum of (A) and (B); and (D) about 5-30 parts by weight of an aromatic phosphoric acid ester per 100 parts by weight of the sum of (A) and (B). The physical properties and flame retardance of the resin compositions according to the present invention are adversely affected by the presence of 3% or more by weight of polycarbonate based on the total weight of the composition.