The present work was conducted during the two wheat growing seasons of 2013/2014 and 2014/2015 respectively, at the Experimental Farm of South Valley University to study the gene action under normal sowing date (30^th November) and late sowing dates (10^th January). Five parents were crossed in ahalf diallel cross mating design. The F₁´s hybrids and their parents were raised under normal and late sowing dates. The analysis of the F₁ generations and their parents revealed that additive gene effects was manifested for all traits studies in the first sowing date, but the reverse was true in the second sowing date. However, over-dominance type of gene action was recorded for grain yield in the first sowing date and partial dominance in the second sowing date. As to the number of kernels/spike partial dominance was displayed in the first sowing date and over dominance in the second sowing date. Narrow sense heritability estimates ranged from 0.49 in the first sowing date to 0.69 in the second sowing date for grain yield. Meanwhile, narrow sense heritability was 0.58 for 1000-grain weight and 0.69 for grain yield in the second sowing date.