Air-jet texturing of conventional poly(ethylene terephthalate) (PET) yarns, having the same chemical structure with high modulus and tenacity PET yarns, are studied in order to improve their adhesion to rubber. Air-jet texturing of these yarns is performed without any visible loop formation in order to minimize the mechanical loss, and an improvement in the adhesion to rubber of conventional PET yarns is achieved. This improvement is investigated by means of surface changes of single. laments and yarn geometry changes due to air-jet texturing. Changes of the cross-sectional structure of the yarns after air-jet texturing and therefore a higher surface area is found to be the main reason for this improvement. (C) 2008 Elsevier B. V. All rights reserved.