Due to high production cost and prevention of environmental pollution, it is important to reduce the amount of nitrogen (N) fertilizer used on wheat (Triticum aestivum L.). The aim of this study was to evaluate N use of 6 x 6 diallel wheat F-2 progenies and parental lines at low (NO, no N fertilizer) and high (N+, 160 kg N ha(-1)) N levels. Significant differences were found between N+ and NO application in grain N content, grain N yield, N use efficiency for grain N yield (NUEgn), and N use efficiency for grain yield (NUEgy). The cultivar '84CTO4' showed positive and high general combining ability (GCA) effects for all traits at low N level. Also, it was the best combiner for all traits at both N levels. The cultivar 'Genc 99' was the best parent for GCA effects for grain yield and NUEgy. Hybrids 'Genc 99 x 84CZT04' and '84CZT04 x Weaver' showed positive specific combining ability (SCA) effects for all investigated traits at low and high N levels. Variety '84CZT04 x Apogee' had the best SCA effects for all traits at low N level. Overall, the data suggest that it is probable to select promising lines suitable for low N conditions by the crossing of high N use efficient parents.