The threat of land degradation by salinization in Jordan has been increasing over the last decades. Therefore, information about the response of local cultivars to salinity is needed to help farmers choose the most productive cultivars for areas with salt-affected soils. A recently released durum wheat cultivar Um Qais (Triticum turgidum subsp. durum) has shown to be productive under normal conditions but to date there are no known studies on its tolerance to salinity. Two experiments were conducted to investigate the response of Um Qais cultivar to salinity. A field experiment was carried out in the Jordan Valley, which is known for its hot, dry climate during the summer and low rainfall and moderate temperature during the winter. Three water salinity levels (S): S1 (2 dS m−1), S2 (4 dS m−1), and S3 (8 dS m−1) with three irrigation amounts (R) (control = 120% (R1), 100% (R2), and 70% (R3)) were used in the field. A greenhouse experiment was conducted using four levels of saline water (S): S1 (0.65 dS m−1), S2 (4 dS m−1), S3 (8 dS m−1), and S4 (10 dS m−1). In both experiments, the leaf area index (LAI) and canopy height were measured during three growth stages, tillering, flag leaf, and maturity. The number of grains, grain yield, and above-ground biomass were measured after harvesting while soil salinity and pH were measured every three weeks during the growing season. The results showed that the maximum reduction in yield was of the 28% in the field experiment when the average soil salinity was of 6.8 ± 1.1 (standard error) dS m−1 at the middle stages of the season. Significant changes were shown in the treatments of the field experiments for maximum LAI, number of grains, and aboveground biomass, but not for plant height. For the greenhouse treatments, about 60% of the maximum grain yield was obtained when the average soil salinity was 9.94 ± 1.89 dS m−1 at the middle stage. Grain yield was the most sensitive parameter to the increase in soil salinity during the season. According to the findings of both experiments, Um Qais can be cultivated in moderately saline soils.