Abstract: A glass fiber-reinforced polyester resin composition consisting of: (A) about 55 to about 95% by weight, based on the total weight of (A) and (B), of poly(tetramethylene terephthalate) resin and a glycol component unit, (B) about 45 to about 5% by weight, based on the total weight of (A) and (B), of a copolyester resin composed of a dicarboxylic acid component unit and a unit of a mixed glycol consisting of a specific ether glycol, and a monoalkylene glycol, the amount X in mole % of the ether glycol being expressed by the formula 12/n.ltoreq.X.ltoreq.150/n wherein n is an integer of 2 to 6, and the amount of the monoalkylene glycol being (100 - X) mole %, (C) about 10 to about 50 parts by weight, per 100 parts by weight of the sum of (A) and (B), of glass fibers, and (D) up to about 50 parts by weight, per 100 parts by weight of the sum of (A) and (B), of an additive.