A filed investigation was conducted at Sakha Agricultural Research Station, A.R.C., Egypt during 2000-2002 growing seasons. The two Egyptian cotton crosses, Giza 45 x Giza 75 and Giza 88 x Giza 89 with their six populations were evaluated for lint yield and lint yield components, seed characters and fiber quality. The data showed significant deviation from zero for the values of A, B and C, indicating the inadequacy of the additive-dominance model and the presence of non-allelic gene interactions for all studied characters, except micronaire reading. Significant epistatic deviations on the basis of F2 mean (E₁) and back crosses mean (E2) for most characters were in complete agreement with the outcome of A, B and C scaling test. All types of gene effects were significant and govern the inheritance of most studied characters. The potence ratio values Indicated overdominance for bolls/plant, seed index and seed density in both crosses as well as 100-seed volume only in cross I, and lint yield/plant, lint/seed, lint percentage and heavy seed percentage in cross II. High to moderate heritability estimates in the narrow sense were found for all characters except seed density, in both crosses, 100-seed volume, heavy seed percentage and Pressley index in cross I and seeds/boll in cross U. Maximum pre Acted genetic advance values as a percent of F2 mean (ag%) were detected for lint yield/plant and bolls/plant in both crosses .Genetic advances were also reported for lint/seed, 100-seed volume and heavy seed percentage in cross H.