Some promising bread wheat lines (Triticum aestivum vulgare L.) generated from interspecific hybridization program at Sids Agricultural Research Station, ARC, Egypt and two standard checks cultivars (Sakha 94 and Sids 1) were evaluated for grain yield performance and its components and phenotypic and genotypic stability across ten environments represent  North, Middle and South Egypt. Results of the combined analysis of variance for the traits under study showed highly significant effects for lines, environments, and line by environment interaction. The means of grain yield for individual lines ranged from 2.42 to 3.18 Kg/plot. When the phenotypic grain yields were subjected to stability analysis against an environmental index according to Eberhart and Rusell (1966), the regression coefficients for individual lines ranged from 0.51 to 1.17. Among the lines tested, lines no. 1, 2, 3, 5, 6, 9, 21 and 22 characterized-on phenotypic stability lines across all environments. Regarding the genotypic stability according to Tai (1971), with probability 90%, lines number 3 and 7 have genotypic stability for grain yield under the ten environment.