The study attempted to characterize Nitrogen Use Efficiency (NUE), nitrogen yield (Yn), and N balance (Nb = N surplus) depending on the dose of the total N fertilization (F = N dose in mineral fertilizers, natural fertilizers, or N from deposition). The study included basic crops in Poland in the years 1999–2014. The determination of the relationships between Yn, NUE, Nb, depending on F was performed using the elements of the methodology proposed by Lassaletta et al. (2014). The evaluation of differences between the optimal NUE and the NUE obtained in this study was carried out using the lower limits of the optimal NUE = 70–90%, as proposed tentatively by the EU NEP (2014). The study indicates that in the period of 1999–2014, NUE of basic crops in Poland increased, achieving the weighted average value of 55%. This value was significantly decreased by low NUE of permanent grasslands (42%), which have the largest share (20.3%) in the structure of land use in Poland. It would, therefore, be recommendable to increase NUE on grasslands. The omission of permanent grassland in the analysis increased the weighted average NUE for basic crops on arable lands to the value of 60%. There were no differences found in the weighted average NUE values in the case of more intensive (60%) and more extensive (60%) crops. Assuming that there is a need to increase NUE to the lower level of the optimal value (70%), we concluded, on the basis of our results and discussion, that the most effective way to achieve it would be to improve the NUE of more intensive crops, especially of wheat, triticale and barley. These plants achieve higher grain yields, Yn, Ymax, and Yn gap. They also have a larger share in the crop structure in comparison with more extensive crops.