Salinity tolerance was tested on four different rootstocks (Mr.S.2/5, G.F.655/2, G.F.677 and peach seedling) commonly used for peach. Plants were salinized by adding 80 or 120 mM NaCl to the standard irrigation solution for 14 days, which followed a twoweek period during which the salt concentration was increased stepwise weekly. Leaf water potential, gas exchange, concentration of Cl-, Na+, K+ and soluble carbohydrates were measured at the end of the experimental period. Salt stress decreased the leaf water potential of all rootstocks. A significant decrease in CO2 assimilation rate (A) was measured in leaves of peach and G.F.677 plants treated with 80 and 120 mM NaCl, whereas a smaller inhibition was observed in those of Mr.S.2/5 and G.F.655/2. The rootstocks (G.F.655/2 and Mr.S.2/5) which showed highest stomatal conductance (gs) prior to the onset of salinization were also the least affected by salt treatments. The G.F.677 and G.F.655/2 accumulated less Na+ in the leaf than the other rootstocks when treated with 120 mM NaCl. The salt-induced increase in leaf Cl" was more similar across the four rootstocks. The leaf sorbitol concentration and the sorbitol/sucrose ratio were significantly increased in salt-treated plum rootstocks, but did not change in the G.F.677 and the peach seedling. However, leaf sorbitol concentrations were highest in control plants of these latter rootstocks.