Wheat crop yield in farmer's fields in Ethiopia is low, <1.0 Mg ha-1, caused by poor soil fertility and nutrient supply. This study investigated the interaction effects of nitrogen (N) and sulphur (S) fertilization on crop yield, N and S uptake, nitrogen use efficiency (NUE), and amino acid composition of two bread wheat cultivars, Shehan and Enkoy. A factorial combination of three N rates (0, 100 and 180 kg N ha-1) and four S rates (0, 20, 40 and 60 kg S ha-1) was applied in randomized complete blocks in three replications. The experiment was conducted at two sites with Andisols and Cambisols. The two wheat cultivars responded significantly (P<0.05) to both N and S applications, showing a strong interaction effect. Grain yield for Shehan and Enkoy cultivars, averaged for both soils, increased by 1.0 and 2.4 Mg ha-1, respectively, with N and S application relative to the control. These significant interaction effects markedly improved the NUE (28%). The N concentration increased significantly from N0 to N2 in both cultivars. There was also a marked N-S interaction on the S concentration of grains. Nitrogen and S fertilization improved considerably the protein quality. The concentration of cysteine and methionine was increased by 27% and 14%, respectively with N and S fertilization as compared to N alone. However, the grains fertilized with N only had higher concentration of asparagines, glutamine and proline and lower concentration of valine leucine, isoleucine and lysine. The grain yield, NUE, N and S uptake, and the S-amino acid concentration of Enkoy were significantly higher than Shehan cultivar showing a strong varietal difference. The results suggest that fertilization of N with S is very essential for increasing the grain yield, nutrient uptake and NUE and for improving the quantity and quality of protein in grains of these culivars.