Researchers investigated the dimensional and physical properties of plain jersey and lacoste fabrics manufactured from cotton ring and rotor spun yarns on a circular knitting machine equipped with a positive feed system. Results revealed that structural differences in the yarn dictated the dimensions and behavior of both fabric types. The amount of relaxation shrinkage occurring in fabrics manufactured from open end yarns was greater than that in fabrics manufactured from ring spun yarns. Because rotor spun yarns were weaker and reduced bursting strength, fabrics knit from rotor spun yarns pilled more. In addition, knit fabrics manufactured from rotor spun yarns exhibited slightly poorer abrasion resistance. 6 refs.