The presence of genotype by environment interaction complicates selection of superior genotypes. The study was conducted to evaluate the effect of GEI and its magnitude on the grain quality of bread wheat genotypes in Ethiopia. 15 bread wheat genotypes were evaluated using RCBD with 4 replications at 6 different locations in Ethiopia. Analysis of variance showed highly significant (P<0.001) differences among genotype, environment and its interactions for investigated quality properties. The results showed that the genotype ETBW9045 had excellent HLW followed by ETBW8070 (73.38 kg/hl) and ETBW8065 (73.02 kg/hl), while the lowest mean values of HLW was obtained from genotype ETBW9464 (66.58 kg/hl) and genotype ETBW9470 had excellent TKW followed by ETBW8427 (39.22 g), while the lowest was that of ETBW8075 (27.32 g). The mean value of moisture content of wheat genotype was ranged from 10.5% to 10.99%. In this result protein content varied from 13.93 to 15.05%. Genotype ETBW8065, ETBW8484 and ETBW9464 gave the best value of protein in the favorable means (15.05%, 14.76% and 14.64%) respectively, while the genotype ETBW9470 had lowest mean value of protein. The Hidase had the highest value of wet gluten (58.2% ) and dry gluten(24.38% ) in average for all investigated locations (58.2%), while lowest wet gluten and dry gluten was obtained from genotype ETBW8427 with the value of (36.49%) and 12.81% respectively. The results showed that genotype ETBW9037 had the highest (82.23%) mean value of gluten index while genotype Hidase had the lowest (58.55%) mean value. Regarding the environments, the highest mean values of HLW for all genotypes were at Holeta (75.68 kg/hl), while the lowest values were at Asasa (66.42 kg/hl). The highest mean values of TKW were recorded at Arsi Robe (38.97 g) and lowest mean value at Asasa (30.89 g). According to locations means, both protein and wet gluten content the highest wet gluten was measured at location Dera, while the lowest at location Arsi Robe. The highest mean value for gluten index obtained were 78.18% at Asasa, while the lowest value (60.36%) was observed at Holeta.