AbstractTwo spring wheat cultivars (Triticum aestivumL. em Thell.), one tall (Chris) and the other semi‐dwarf (Era), with different yields and grain protein potentials, were grown in controlled environment chambers to compare the nitrogen fractions, amino acids and nutritional quality in developing grains at 12, 22, 29 and 36 days after heading. The proportions of gliadin I, gliadin II and glutenin II increased and those of albumin and globulin decreased as the wheat cultivars matured. The amount of lysine, methionine, threonine, valine, tyrosine, alanine, aspartic acid and glycine was lower and that of glutamic acid and proline was higher with grain development in both cultivars. At 12 days after heading Era had a higher content of amino acids (16 g−1N) than Chris. Isoleucine was the first limiting amino acid in Era and Chris at the first collection period whereas at later stages lysine was the limiting amino acid in both cultivars. Chemical score, essential amino acid index, requirement index and calculated biological value all decreased as the grain matured and, except for the 12‐days collection period, the data were almost similar for both the cult