This thesis which was an attempt to a comparative study of ring spun yarn and rotor spun yarn on the mechanical and comfort property of single jersey fabrics 28 Ne 100% cotton yarn were spun from the same carded slivers of the same mixing using ring spinning machine and rotor spinning machine of MAA garment industry. These yarns were separately knitted on a circular knitting machine to make two types of single jersey fabrics using the same knitting machine and parameters. The fabrics thus knitted were tested for their mechanical properties such as bursting strength, abrasion resistance and pilling resistance. They were also tested for their comfort properties such as air permeability, compressibility and surface friction, the results were studied and analyzed using ANOVA and the results shows that bursting strength of ring spun knitted fabric (6.82 bar) is greater than rotor spun knit (4.834 bar), as far as Abrasion resistance concerned ring spun yarn (1.32 %) have less weight loss than rotor spun yarn (3.03%) and ring spun yarns tends to pill more than rotor spun yarn. The fabrics knitted from rotor spun yarn (161cm3/ cm2 /s) have higher air permeability value than ring spun knitted fabric (134cm3/ cm2 /s). The fabrics knitted from ring spun yarn have higher roughness value than rotor spun yarn. So far as compression property is concerned the fabrics knitted from rotor spun yarn have higher compression value than ring spun yarn. It has been found that the yarn property and its structure has got significant influence on both the mechanical and comfort properties.