Water deficit inhibits photosynthesis and N₂ fixation in soybean [Glycine max (L.) Merr.], and published results concerning relative sensitivity of these processes to water deficits are inconsistent. The objective of this research was to evaluate shoot N concentration in plants exposed to water deficits relative to N concentrations in well-watered plants as an indicator of the relative sensitivity of N₂ fixation and photosynthesis to water deficits. Shoot biomass accumulation and N concentration were determined under well-watered and water-deficit conditions for a total 113 genotypes under field or greenhouse conditions. Shoot N concentration among genotypes under well-watered conditions ranged from a low of 20 g N kg^-1 shoot dry weight to a high of 40 g N kg^-1 of shoot dry weight. In response to water deficit, shoot N concentrations increased relative to well-watered plants for genotypes with a low well-watered N concentration and decreased for genotypes with high well-watered N. As a result, all genotypes had more intermediate shoot N concentration following water-deficit stress, with an approximate range of only  5 k N kg^-1 between the low and high N genotypes following a 2- to 3-wk exposure to water-deficit conditions. There was no influence of well-watered N on biomass accumulation rate under well-watered or water-deficit conditions. These results indicate that drought-tolerance of N₂ fixation may be associated with low shoot N concentrations under well-watered conditions.