Nitrogen use efficiency of durum wheat grain (Triticum turgidum ssp. durum), as valuable indicator for rational N fertilization supply, was investigated in a field experiment in the subhumid area of Tunisia with four durum wheat genotypes: two improved genotypes and two landraces, grown under three mineral N fertilization treatments (0,75 and 150 kg N ha-1) during two cropping seasons (2008/09, 2009/10). Total N content in grain, yield, N uptake by grain, and soil N (N-NH4, N-NO3) status were examined to indicate relations between N trial treatments and growing years. Analysis of variance indicated that significant interaction was noted for nitrogen x years and genotypes. Over total investigated period, above-mentioned factors significantly differ per nitrogen levels and years. The highest total N content in durum wheat grain was recorded in N150 treatment during 2009/10, but the highest yield was reached in 2008/09 growing season under 150 kg N ha-1. Drought and elevated temperatures prevailing during 2009/10 cropping season were associated with lower yielding ability of most genotypes along with higher NUE per fertilization treatment, compared to 2008/09. NUE values varied from 7.85% in 2008/09 up to 24% in 2009/10 for the 150 kg N ha-1 treatment. During investigated growing years NUE was increased with increasing nitrogen fertilization levels.