With 200 mmol/L NaCI treatment on barleycultivar "Jian 4" (Hordeum vulgare L. cv. J4) seedlings for6 d, the contents of covalently and noncovalently conjugatedpolyamines (PAs) and activities of H+-ATPase in plasmamembrane (PM) vesicles isolated from the roots decreasedremarkably. Moreover, the activity of Na+/H+ antiport wasdetected first in PM vesicles. The results showed that thedecrease in the contents of membrane phospholipid, nonco-valently conjugated PAs and activity of H+-ATPase caused byNaCl could be restored partially by application of 1 mmol/Lstearic acid (C16:0) and linoleic acid (C18:2), and C18:2 wasmore effective than C16:0. In addition, a reduction in the con-tents of covalently conjugated PAs was only reversed par-tially in the presence of C18:2. Furthermore, Na+/H+ antiportactivity was strengthened by exogenous C16:0 and C18:2, andC18a was more effective than C16:0. The correlative analysissuggested that, after application of C16:0 and C18:2 under saltstress, there was a significant positive correlation existingamong phospholipid content, noncovalently conjugated PAlevels, H+-ATPase activities and Na+/H+ antiport activities,indicating that one of the mitigative mechanisms of exoge-nous fatty acids on salt injury was to improve membranephospholipid and PA contents, leading to an enhance inmembrane integrity and a change in charge status of PMvesicles, so the activity of membrane-associated enzymeH+-ATPase was increased and synthesis of Na+/H+ antiportprotein was activated.