The present study was carried out at EL-Mattana Agricultural Research Station during 2000/2001, 2001/2002 and 2002/2003 seasons. Diallel cross without reciprocals among seven parents of durum wheat namely: Kucuk (P1), Rascon / Kitti (P2), Bani-Sweif 1 (p3), Terbol 97-4 (P4), Waha (P5), Sohag 2 (P6), and Sohag 3 (P7) were used to estimate heterosis, general and specific combining ability, phenotypic correlation for yield and its components, as well as some other agronomic characters in the F1 and F2 generations. Mean squares reflected the highly significant differences among genotypes, parents and crosses for all studied characters in the F1 and F2 generations. Moreover, both general and specific combining ability (GCA and SCA, respectively), were significant for all studied characters in the F1 and F2 generations. The estimates of heterosis for grain yield /plant indicated that seven crosses out of 21 F1 hybrids significantly surpassed their better parent with percentage ranged from 8.41% for P3 xP6 to 49.41% for P1 xP3. These relatively high heterotic percentages along with the variability existed among all diallel set increase the chance of good recombinations that can be isolated in the following generations particularly, when selfing in the following generations gives an essentially homozygous state and enhances the role of selected plants in reducing the effects of dominance. However, the additive gene action was of great importance in the performance of most studied characters. Moreover, the parents P6 (Sohag 2) was the best combiner for seven characters while, P2 (Rascon/ Kitti) was the best for only four out of the eight characters in the F1 hybrids. Meanwhile, significant SCA effects for grain yield were found in ten out of the 21 F1 crosses giving positive values of SCA effects. On the other view, F2 population, eight crosses gave positive values of SCA effects. The additive variance effects were significant for all studied characters except for number of spikes/ plant and grain yield /plant in the F1 crosses and number of kernels /spike and grain yield /plant in the F2 generations. Moreover, positive correlation values were observed between grain yield /plant and each of the following studied traits, number of kernels/spike and number of spikes/plant, whereas low positive correlation was found between days to maturity with grain yield /plant in the F1 hybrids. These results indicated that selection in segregating generation could be effective to produced high yielding lines.