Resumo. The objective of this study was to evaluate the effects of increasing sodium chloride (NaCl) concentrations on quantum potential efficiency of the photosystem II (Fv/Fm), index of the intensity of the green color in leaves (SPAD value), dry leaf biomass, leaf area and potassium (K) and sodium (Na) concentrations in Eucalyptus seedlings leaves. The experiment was carried out in a green house, using 11.5 L pots filled with sand and irrigated with nutrient solution, in Campos dos Goytacazes (RJ). The experiment was set up according to a completely randomized factorial design, with four species (Eucalyptus camaldulensis, Eucalyptus tereticornis, Eucalyptus pellita and Eucalyptus robusta) and five saline levels (1.41; 2.50; 4.50; 6.45 and 8.33 dS m-1), with five replicates. Up to the maximum applied saline level, seedlings of Eucalyptus camaldulensis, Eucalyptus tereticornis and Eucalyptus robusta showed positive responses regarding SPAD values and quantum potential efficiency of the photosystem II, dry leaf biomass and leaf area. These evaluations suggest tolerance of these species to saline conditions. Seedlings of Eucalyptus pellita showed sensitivity to saline stress. The reductions of dry leaf biomass and leaf area may be related to seedling resistance to saline conditions.