Cucumber (Cucumis sativus L.) plants were precultured for 7 days in either optimal (10 µm) or low (0.5 µm) Fe conditions and then grown for further 5 days in a N-free nutrient solution with (+Fe) or without (–Fe) 10 µm Fe. Thereafter NO₃^– (4 mm) was added to the nutrient solution for 24 h and, concomitantly, half of the –Fe plants were treated with 1 µm Fe complexed to water extractable humic substances (WEHS). Supply of NO₃^– to +Fe–N-deprived plants caused a large induction in the capacity to take up the anion by roots, which was accompanied by a rise in root–shoot NO₃^– concentration. The –Fe plants showed a lower level of induction of NO₃^– uptake and hence a lower accumulation of the anion in the tissues, these effects being reversed by supply of Fe-WEHS. Supply of either NO₃^–- or NH₄⁺-N (+/– Fe-WEHS) to –Fe plants promoted the development of the root Fe^III-chelate reductase activity, but the capacity of roots to take up the Fe²⁺ remained unaffected. Results show that an inadequate Fe supply can limit the acquisition of NO₃^–, whereas NO₃^– supply can affect Fe uptake by influencing the development and maintenance of a high Fe^III-chelate reducing capacity.