Statement of the problem : There is a deficiency in both aesthetic and functional properties of cotton yarns (carded, combed) and thus the fabrics produced from them (weaving, knitting, domestic fabrics) manufactured from the most spinning methods achieving the aesthetic and functional properties of yarns "compact spinning". In order to contain the yarns on a fair number of dead, immature and short fibers, which are inflexible because these fibers are hollow with a few convolutions in it, which causes their conglomeration and cohesion with each other during the spinning process so-called "Neps" and hairiness. Which is detrimental to the appearance and regularity of both cotton yarns and fabrics especially after the final processing. In terms of functionality, these imperfections (IPI) reduce the tensile strength, elongation, uniformity of yarns, their resistance to wrinkle, friction due to the weakness of flexibility and softness, which leads to shortening the life span of fabrics produced from them. Increases such imperfections (IPI) clearly in both yarns and fabrics, especially with the low quality of current Egyptian cotton grades.Results: The correlation coefficient was extracted and the regression line equation for the different relationships between the different gassed yarns count of the different types (carded, combed) after mercerizing process and : The yarn tensile strength, Breaking Elongation, Yarn Hairiness, Yarn Imperfection (IPI), Yarn T.P.I, yarn Humidity, Gassed yarn count before mercerizing. It was found that; The yarn count of both carded compact cotton gassed yarns and combed compact cotton gassed yarns reduced by cotton count system after mercerizing process-using tension for many reasons, Yarn tensile strength increased for both carded compact cotton gassed yarns and combed compact cotton gassed yarns after mercerizing process-using tension for many reasons, Breaking elongation ratio of both carded compact cotton gassed yarns and combed compact cotton gassed yarns reduced after mercerizing process-using tension for many reasons, Yarn hairiness disappeared completely in carded compact cotton gassed yarns, especially in combed compact cotton gassed yarns after mercerizing process-using tension for many reasons, Yarn imperfection (IPI) ratio significantly reduced which is the sum of both (thin places, thick places, Neps) for both carded compact cotton gassed yarns and combed compact cotton gassed yarns after mercerizing process using tension for many reasons, Yarn T.P.I reduced in both carded compact cotton gassed yarns and combed compact cotton gassed yarns after mercerizing process using tension for many reasons, Yarn humidity ratio increased in both carded compact cotton gassed yarns and combed compact cotton gassed yarns after mercerizing process-using tension for many reasons.