During 2010 and 2011seasons, two field experiments of rice experimental farm of Sakha, Kafr El-Sheïkh, Egypt, were performed through a 6 x 6 diallel system analysis to investigation the combining ability and heterosis and their component features of rice under normal irrigation and drought stress conditions.A broad range of genetic variation among research genotypes was indicated by the routine analysis of variance. As for all the features of normal irrigation and drought stress conditionsThe significance of non-additive genetic variation in the heritage of grain yield / plant has been established by GCA / SCA ratios. While the selection based on the accumulation of the additive effect will boost yield and assign it successfully. According to drought susceptibility index (DSI), four parents and six crosses were the lowest genotypes affected by drought.GCA shows all parental lines are intrinsically performing with a strong index of their overall ability to blend. The combinations of IR7887-176-B-2-B X IR80508-B-194-1-B to boost the output of grain per plant was the best possible cross, as reported by SCA.Under drought, the highest values significant for heterosis from better parent, five crosses for panicle length and seven crosses for number of branches / panicles and grain yield characters. In the general sense, higher heritability levels emerged in normal irrigation; genotypic variances played a major part in phonotypical yield variances and their components.Lower and moderate heritage tests for all yields and their components showed that selection for these characteristics would be successful in late generations.