his research was conducted to determine genetic gain of predicted response to selection (genetic advance), realized response to selection (observed), generalized selection and selection differential as well as heritability, phenotypic and genotypic coefficients of variation to improve for boll weight, lint percentage, fiber length, fiber strength and fiber fineness. The materials used were the three generations F2, F3 and F4 of the three Extra -Long cotton crosses Giza 87 x C. B 58 (pop. I), Giza 93 x Giza 71 (pop.II) and Giza 92 x Pima High Lint percentage (pop.III) were grown at Sakha Agricultural Research Station during (2013 – 2015) seasons. The results could be summarized as follows: The realized means of F4 were higher than the realized means of F3 and F2 but lower than the means of the selected families of the three cycles indicating response to selection and subsequently improvement for all traits. Predicted response to selection (G.A) was greater than realized response to selection for boll weight, fiber length and fiber strength indicating that dominance gene effects were controlling the inheritance of these traits .For lint %, the realized response was higher than the predicted response to selection in the first cycle of (pop. II). The realized response was higher than the predicted response to selection for fiber fineness in second cycle of (pop. III), indicating that additive gene effects were predominant in the inheritance of lint% and fiber fineness. The low value of micronaire readings were desirable in (pop. II). This finding was in harmony with the high value of heritability in F2 and F3 for lint % and fiber fineness respectively. Realized selection differential values were greater than predicted selection differential for lint % in (pop. I) and (pop .II), while in (pop. I) for fiber strength, boll weight and fiber length in (pop. II). Heritability values were high for lint % in the three generations and boll weight in F3 of (pop. III), as well as fiber traits in F2 and F3 generations of (pop. II) and (pop. III). Phenotypic coefficients of variation were larger than genotypic coefficients of the three populations. It could be concluded that of the effective breeding method for improving lint % and fiber fineness of the two populations, (Giza 93 x Giza 71) and (Giza 92 x Pima High Lint percentage) because of the high heritability values and additive gene effects.