This work was carried out in the Laboratories of Technology, Division, Cotton Research Institute, and Agricultural Research Center Giza, to investigate the effect of trash content on fiber quality. Six of the commercial varieties of Egyptian cotton, were taken in the study, three extra-long staple categories, (Giza 45, Giza70 and Giza 88), delta long- staple categories, (Giza 86), and two Upper Egypt long- staple categories,(Giza 80and Giza 90), grown in 2012-2013 season. All tests were done under controlled atmospheric conditions of 65±2% relative humidity and 70±2ºF temperature at the study the effect of the trash content on: spain length at 2.5%, (ML 2.5%) mm, uniformity ratio (Ur%), fiber strength   in gram/tex. St. (g/tex) fiber elongation% (Elon. %), micronaire reading (Mic.) reflectance degree (Rd %) and yellowness (+b). The following fiber properties were measured using high volume Instrument (HVI). High volume fiber test system according to American Standard Testing and Materials (ASTM), (1998) and Digital fibrograph: according to ASTM (1977), prior to testing the lint cotton sample was stored and tested in a controlled atmosphere of (65±2%) relative humidity and 21±2°C. All the characters were significant, and correlated negatively to the increment of trash content accepted the reflectance degree (Rd %), spain length at 2.5%, (ML 2.5%), fiber strength   in gram/tex. St. (g/tex), micronaire reading (Mic.) characters which, correlated positively with trash content at the yellowness degree (+b). The trash content accepted were increasing, at 1% the lowermost values ​​decreasing on: ML 2.5%, Ur%, St. g/tex, Elon.%, Mic and Rd%. But yellowness (+b) increasing. The diffraction increasing or decreasing, in the varieties. The maximum values ​​decreasing and the first arrangement (realigning) is by fiber elongation% they micronaire reading they strength they the reflectance degree (Rd %) they spain length at 2.5% and uniformity ratio. The trash content effected were arrangement (realigning) diffraction in the all varieties at the values characteristics.