Soil-borne amino acids may constitute a source of nitrogen (N) for plants in various terrestrial ecosystems but their importance for total N nutrition is unclear, particularly in nutrient-rich arable soils. One reason for this uncertainty is lack of information on how the absorption of amino acids by plant roots is affected by the simultaneous presence of inorganic N forms. The objective of the present study was to study absorption of glycine (Gly) and glutamine (Gln) by wheat roots and their interactions with nitrate (NO<sub>3</sub><sup>−</sup>) and ammonium (NH<sub>4</sub><sup>+</sup>) during uptake. The underlying hypothesis was that amino acids, when present in nutrient solution together with inorganic N, may lead to down-regulation of the inorganic N uptake, thereby resulting in similar total N uptake rates. Amino acids were enriched with double-labelled <sup>15</sup>N and <sup>13</sup>C, while NO<sub>3</sub><sup>−</sup> and NH<sub>4</sub><sup>+</sup> acquisition was determined by their rate of removal from the nutrient solution surrounding the roots. The uptake rates of NO<sub>3</sub><sup>−</sup> and NH<sub>4</sub><sup>+</sup> did not differ from each other and were generally about twice as high as the uptake rate of organic N when the different N forms were supplied separately in concentrations of 2 mM. Nevertheless, replacement of 50% of the inorganic N with organic N was able to restore the N uptake to the same level as that in the presence of only inorganic N. Co-provision of NO<sub>3</sub><sup>−</sup> did not affect glycine uptake, while the presence of glycine down-regulated NO<sub>3</sub><sup>−</sup> uptake. The ratio between <sup>13</sup>C and <sup>15</sup>N were lower in shoots than in roots and also lower than the theoretical values, reflecting higher C losses via respiratory processes compared to N losses. It is concluded that organic N can constitute a significant N-source for wheat plants and that there is an interaction between the uptake of inorganic and organic N.