Most of the major stem rust resistance genes deployed in commercial durum wheat cultivars and breeding lines were succumbs to emerging races. Breeding wheat for rust resistance to stem rust is a priority work worldwide including Ethiopia. Due to the diversity of stem rust races in Ethiopia; almost all cultivars are susceptible to the existing races at adult plant stage. This study was initiated to determine the effectiveness of durum wheat germplasm to multiple stem rust races (TTTTF, TTRTF and JRCQC) of Puccinia graminis f.sp. tritici at seedling and Adult plant growth stages in Ethiopia. During 2019 and 2020, a total of 156 durum wheat germplasm consisting of released varieties, landraces and advanced lines were evaluated against three P. graminis f.sp. tritici races at seedling stage in greenhouse and at adult plant growth stage in single race nurseries. Most of the germplasms were susceptible to the three stem rust races at adult plant stage. About seven germplasms (two cultivar, two landraces and three CIMMYT advanced lines) showed adult plant resistance to the three races and showed high infection type (3-4) at seedling stage. The responses of the durum wheat lines across races were positively correlated. Durum wheat lines which exhibited resistance to TTRTF and JRCQC were susceptible to TTTTF race both at seedling and adult plant growth stages. This study confirmed the importance of testing durum wheat germplasms to multiple races of P. graminis f.sp. tritici both at seedling and adult plant growth stages.