Abstract: Textured polyester multifilament yarn having uniform quality in dye-absorbing properties and crimp properties is produced by a combined draw-texturing method wherein a feed yarn composed of a plurality of polyester filaments having a birefringence of at most 0.04 is drawn and simultaneously or sequentially textured, said feed yarn being produced by meltspinning a synthetic linear ethylene terephthalate polymer to form an undrawn multi-filament yarn, winding up the undrawn yarn and, before and/or after the winding operation, applying to the undrawn yarn a finishing agent which is not capable of diffusing into the inside of the filaments but is capable of preventing protuberance formation at a surface protuberance number larger than 5 on the surface of the filaments when the feed yarn is aged at a temperature of 40.degree. C at a relative humidity of 70% for 21 days and, then, twisted at a twist number of 32500/.sqroot.D turns/m, wherein D represents a denier of the feed yarn, without drawing.

Abstract: A false twist-crimped polyester yarn having a density (d) of 1.3800.ltoreq.d.ltoreq.1.3970 (g/cm.sup.3) and total percentage crimp (TC) of TC 30% is produced by false twisting a polyester multi-filament having a birefringence (.DELTA.n) of 0.030.ltoreq..DELTA.n.ltoreq.0.145 while heat setting the filament in the twisted state at 160.degree. to 210.degree. at a draft (dr) which satisfies the following equation:-150(.DELTA.n) + 17.ltoreq.dr.ltoreq.0.9 .times. 10.sup.4 (.DELTA.n.sup.2)-29 .times. 10.sup.2 (.DELTA.n)+248.