A half diallel set involving six diverse parental sesame genotypes and their F1 were evaluated at Ismailia Agricultural Research Station, ARC, Ismailia Governorate, Egypt using a randomized complete block design with three replications. Highly significant genotypes and its components (parents, hybrids and parents vs. hybrids) mean squares were detected for all studied traits. Highly significant mean squares were associated with general (GCA) and specific (SCA) combining ability for all studied traits. Also, additive gene action in genetic control of most studied traits was observed. The parent P5 seemed to be the best combiners for seed yield/fad and one or more of its components. The most desirable inter- and intra-allelic interactions (SCA) were detected in F1 hybrids, P5 x P6 and P1 x P3 for seed weight plant-1 and P1 x P3 and P2 x P4 for seed yield fad-1which also revealed the highest heterotic effects over mid and better parents. Significant or highly significant values and high values of the dominance component (H1) were also observed for the most studied traits indicating the presence of over-dominance and its confirmed by (H1/D)0.5(more than 1). The parents of P2 and P4 for seed weight plant-1 and P1 and P4 for seed yield fad-1 carried the most dominant genes responsible for the expression of these traits, In the contrary P5, P3 and P6, for seed weight plant-1, and P5, for seed yield fad-1, possessed high concentration of recessive genes.