The present work was conducted to study the effects of late planting on the performance of Egyptian cottons and to obtain information concerning the genetic control of earliness, lint yield/plant, lint% and lint index. Half diallel crosses among seven Egyptian cultivars were evaluated in the F2-generation under early and late planting conditions for two seasons. The reduction% in lint yield/plant caused by late planting was very high and reached 73.92% for the parents and 68.27% for the F2-populations. Both additive and non-additive gene effects were involved in the inheritance of days to first flower, earliness index, lint yield/plant, lint% and lint index, but the non-additive was much larger than the additive gene effects. Epistatic gene effects were found in the earliness traits and lint index in the second season, lint% and lint yield/plant in early planting in the second season. The graphics of Wr/Vr analysis for lint yield indicated that the distribution of the parents around the regression line was not consistent in both of early and late plantings in the two seasons. The genetic parameters indicated unequal distribution of dominance and recessive genes in the parents for all traits. The non-additive effects of genes were reflected in the departure from broad to narrow sense heritability. Therefore, pedigree and recurrent selection methods could be effective in late segregating generations. The promising F2-populations were “Giza 90 x Giza 80”, “Giza 90 x Giza 88”, “Giza 90 x Giza 86” and “Giza 86 x Giza 80”.