Half diallel among six Egyptian cotton varieties were used for yield and its components and fiber quality. Results illuminated that mean squares of each genotype (G), Parents (P), Crosses (C), (P vs C), general (GCA) and specific (SCA) combining ability were significant or highly significant for most studied traits. Mean performances of most the 15 F1 hybrids were better than their corresponded parents. Parental varieties recorded variable performances for studied traits. Giza 95 (P2) followed by Giza 94 (P1) were superior for most yield traits and also, Giza 94 (P1) followed by Giza 75 (P3) which possessed best values for all fiber quality traits. Diallel cross analysis exhibited that, the cross P4 x P6 gave the highest SCA effects (Ŝij) for B/P, SCY/P, LY/P and FF. Furthermore, the crosses P1 x P3, P2 x P5, P2 x P3, P3xP6 and P2xP6 were desirable for BW, L%, FS, UHM and UI, respectively. Magnitudes of SCA variance were larger than those of GCA variance, for all studied traits except for L% indicating the predominance of non-additive genetic variance in the inheritance of these traits. It could be concluded that yield components and fiber properties, were mainly controlled by dominance variance effect. The estimated heritability values in broad sense (h2b.s.%) were larger than the heritability values in narrow sense (h2n.s.%) for all studied traits.