Generation means analysis was carried out using five parameters model on three bread wheat crosses combinations, cross 1 (Sids 1 x Sakha 93), cross 2 (Gemmeiza 7 x Giza 168) and cross 3 (Sids 4 x Sahel 1) with five generations (P1 , P2 , F1 , F2 and F3 ) evaluated from 2008/09 until 2011/12 seasons. The objective of this study was to determine nature of gene action controlling yield and its components i.e. days to heading, spike length, number of spikes / plant, number of kernels / spike, 100-kernel weight and grain yield/plant in three wheat crosses grown under normal irrigation and drought stress. Additive (d) was highly significant and positive for most traits in all the three crosses under normal irrigation and drought stress, suggesting the possibility of obtaining further improvements of these traits using a pedigree selection program. The estimates of dominance effects (h) were significant and positive for the most traits in all the three crosses under normal irrigation and drought stress, indicating the importance of dominance gene effects in the inheritance of these traits. The interaction effects together i.e. additive x additive (i) and dominance x dominance (L) found in higher magnitude than the combined main effects of additive (d) and dominance (h) effects for the most traits studied in all the three crosses under normal irrigation and drought stress. Among the interaction effects additive x additive (i) was predominant over dominance x dominance (L) for the most traits in all the three crosses. Positive heterotic effects relative to the mid-parents were found for all the traits studied in the three crosses, except for heading and spike length in the third cross under normal irrigation and drought stress. On the other hand, positive heterotic effects relative to the better parent were found for all the traits studied with some exceptions. Highly significant negative inbreeding depression estimates were detected for days to heading, meanwhile highly significant positive inbreeding depression estimates were shown for the other studied traits in all crosses. Also the amount of inbreeding depression was higher in F3 than F2 generation. The values of narrow sense heritability in F3, were more than 24.14% and 26.77% under normal irrigation and drought stress, respectively, and the expected gain from selection suggested that desirable segregates for yield and its components could be expected in subsequent generations. The expected genetic advance as percent of F2 ranged from 10.27% for number of kernels/spike in third cross to 96.64% for number of spikes/plant in the first cross under normal irrigation and ranged from 13.31% for days to heading in the third cross to 98.04% for spike length in the second cross under drought stress. The most promising crosses were the first and third crosses, were found to higher in magnitude which had high genetic advance associated with high heritability and would be interest in breeding programs for improving the yield and yield components traits in bread wheat under normal irrigation drought stress.