This research studies the properties of a plain knitted fabric made from cotton/T‐400 ring core spun yarn and 100% cotton ring spun yarn. Properties of plain knitted fabric made from 100% cotton ring spun yarn were compared with one made from cotton/T‐400 (70.4C/29.6T). We focused on knitted fabric properties such as the bursting strength, elongation at break, tensile strength, air permeability as well as pilling properties. The two yarn samples were produced on the ring frame which had a special attachment for core spun yarn. Fabrics were then knitted using a circular machine, for consistence of results plain knit structure was adopted for all samples. Knitted fabric properties were then tested and results statistically analyzed. Research results show that, plain knitted fabrics made from cotton/T‐400 (70.4C/29.6T) ring core spun yarn exhibit better elongation at break, bursting strength and air permeability. Whereas the fabric made from 100% cotton showed better pilling resistance and tensile strength compared to cotton/T‐400 (70.4C/29.6T) plain knitted fabric. Results show that T‐400 filament has very significant influence on resulting fabric properties and hence can be technically manipulated to suit different fabric end use requirements.