The present study was undertaken to investigate the effect of twist multiplier and back roller cot hardness on the characteristics of PES/CO-blended ring-spun yarn. Yarn samples of 15 tex were spun from three blend ratios, i.e., PES/CO 30/70, 50/50, and 70/30 at ring frame at seven different twist multipliers and three back roller cot shores. Yarn samples were analyzed at Uster Tester 4 and Uster Tansorapid 4 for evenness and physical properties, respectively. The results indicate that hairiness is inversely related to twist multiplier, whereas yarn physical properties improved in PES/CO 30/70 with addition of twist and an inverse trend was observed in other two blend ratios. Back roller cot hardness has positive correlation with CV% and imperfections and negative correlation with yarn physical properties.