Abstract: Improvement of seed yield components and resistance to diseases in sesame crop is the prime objective of a breeding programs. However, little genetic information is available for these approaches listen. Hence, the main objective of this study was to approximate the genetic parameters of seed yield components and resistance degree of Fusarium wilt and charcoal root-rot diseases. Therefore, six promising sesame lines as a hybrids and segregates line (H₁, H₆, H₉, S₂, S₃ and S₅) and Taka 2, a new variety were crossed in all combination using a diallel mating scheme without their reciprocals. Crosses were selfed to obtain seeds of F₂ generation. Progenies of F₁'s and F₂'s along with their parents were evaluated in two separate set of experiments at private farm in Abou Soltan village, Ismailia, Egypt during 2010 crop season. The results exhibited that the GCA mean squares were significant for all characters through both analyses (F₁'s and F₂'s). Positive and significant GCA effects for seed yield (g plant^-1) and seed yield (kg ha^-1) were found for sesame parental lines. S₂ (P₂) indicates that progeny with those genotypes as parents showed a seed yields with the genotype that was greater than the average of all crosses. Parental line S₄ (P₄) was the best combiner for developing genotypes with high oil seed content as well as resistance to F. oxysporum (FOS) and M. Phaseolina (MPH). For achieving genotypes with short time to flowering and plant height, fruiting branches number (plant^-1), capsules number (plant^-1),1000 seed weight (g) and seed yield (kg ha^-1), S₆ (P₆) and Taka 2 (P₇) were the best parents. GCA/SCA ratio indicated additive effects for all the characters except seed yield (g plant^-1) in F₁'s and F₂'s and seed yield (kg ha^-1) only in F₂'s. Narrow sense heritability varied from 89.14% for plant height to 8.79% for seed yield (kg plant^-1). However, most of characters studied scored highest values of bored sense heritability (>75%) except seed yield (g plant^-1) (69.10, 73.21%) seed yield (kg ha^-1) (74.69, 63.28%), infection (%) by FOS (74.99, 64.95%) and infection (%) by MPH (67.32, 71.69%) in F₁'s and F₂'s, respectively. Positive with highly significant association coefficients between GCA effects and mean characters in all cases implied that parental sesame lines with high values of the characters have superior combining ability. The phenotypic (r_ph) and genotypic (r_g) coefficient between all studied characters shows negative to positive values with significant or non-significant correlation between each of both characters through F₁'s and F₂'s. It was noticed that the high resistance characters give the lowest seed yield. Therefore, a great care should be taken during selection for seed yield and its components as well as the resistance to infection (%) by each of FOS and MPH.