This study was carried out at Karahta station, Department of Field Ccrops researches, General Commission for Scientific Agriculture Researches (GCSAR), Damascus Country Side, Syria during the 2009-2010and 2010-2011 growing seasons to estimate gene action for grain yield and its components. Seeds of the durum wheat hybrid (Sham5 X Azgar1) were grown in three replicates. Results indicated that the used genotypes had good variation to be used as parents in wheat hybridization program to achieve significant genetic advance. Mean square results showed significant differences among mean values of the five populations for all studied traits in the hybrid and in most traits, epistasis or dominance gene action occupied the first rank to the genetic effects. It was suggested that selection for most studied traits in the subsequent generations is relatively more effective than in early generations.