The main subjective of the present study was to clarify the relationship between technological fiber and yarn traits of some Egyptian cotton varieties. Besides, developing models to predict the most important yarn quality characteristics using the cotton fiber properties attained from HVI and AFIS systems. The current study was carried out using 12 different Egyptian cotton varieties cultivated by the Cotton Research Institute, Agricultural Research Center- Giza, Egypt. The fiber testing was performed, during 2015 season, in CATGO and Eshra tex labs, Alexandria, Egypt. Different models for predicting the most important ring yarn quality traits. Yarn lea product, single yarn strength, yarn evenness CV% and yarn work of rupture was developed using HVI and AFIS data and multiple regression equations. The prediction equations attained using AFIS data showed goodness of fit statistics and high R² more than HVI equations. The HVI fiber (U.H.M) length parameter recorded the highest relative contribution percentage to the single yarn strength, yarn evenness CV% and yarn work of rupture (W.R.). Meanwhile, micronaire value recorded the highest relative contribution percentage to the lea product only. The mean length (L _(w) in mm) by weight measured by AFIS instrument possessed the highest relative contribution percentage to the lea product and single yarn strength. While the upper quartile length (U.Q.L in mm) and fiber fineness recorded high convergence contribution to the yarn evenness CV%. The Mean value of length variation, by number (L _(n) CV%) recorded the highest relative contribution to the yarn work of rupture (W.R.).