Vegetative N is remobilized and contributes to seed yield and seed composition. Genotypic variation of tissue N concentration was assessed in a large number of plant introductions from maturity group IV – VIII of the soybean germplasm collection, in a recombinant inbred line population, and a number of modern soybean cultivars. All experiments were conducted under field conditions. Leaf, petiole, and stem tissues of plant introductions and modern cultivars were collected at beginning seed fill (R5), and a second time for stem tissue at maturity (R8). Stem samples were harvested from the recombinant inbred line (RIL) population at R5 and R8. Tissue N concentrations in the germplasm collection ranged from 2.5 – 6.4, 0.8 – 3.2, 0.8 – 2.5, and 0.5 – 1.0% for R5 leaf, R5 petiole, R5 stem, and R8 stem, respectively. In the modern cultivars tissue N concentration was examined under irrigated and dryland conditions and with or without applications of large amounts of fertilizer N. The range in tissue N concentrations was 3.5 – 5.5, 1.2 – 2.5, 1.1 – 2.8, and 0.7 – 1.2% for R5 leaf, R5 petiole, R5 stem, and R8 stem, respectively. Stem N concentrations in the RIL population varied between 0.8 – 2.1% at R5 and 0.5 – 1.1% at R8. Significant positive relationships with selected tissue N traits and seed yield were observed. A better understanding of the remobilization dynamics of vegetative N may reveal avenues or breeding strategies for soybean yield and seed quality improvement.