Grain protein is an essential factor determining end-use quality of wheat. Grain producers wanting to capture the economic benefits of protein prize premiums are optimizing nitrogen (N) fertilization of their grain crops. It has been suggested that grain protein concentration (GPC) can be used as an indicator of N sufficiency for optimum grain yield. Although this evaluation would be “after the fact”, it would permit grain producers to judge the adequacy of their fertilization program. The objective of this study was to determine if GPC could be used as an index of N sufficiency for hard red spring wheat grown in the semiarid areas of Saskatchewan.