Two wheat (Triticum aestivum L.) cultivars (salt sensitive cultivar, Gemmieza-9 and salt resistant cultivar, Sids-1) subjected to different seawater salinity (10 and 25%). Osmotic pressure (OP), osmotic adjustment (OA) and solutes accumulation (TSS, TSN, proline, organic acids, glycerol and inorganic ions (Na+, K+, Ca2+, Mg2+ and Cl-) were quantified in flag leaf during grain-filling (14 and 21 days postanthesis). Seawater salinity induced significant increase in osmotic pressure and the magnitude of increase was higher in Sids-1 than in Gemmieza-9. Furthermore, seawater concentrations caused noticeable increase in osmotic adjustment, organic solutes (TSS, TSN, proline, organic acids and glycerol) and inorganic ions (Na+, K+, Ca2+, Mg2+ and Cl-). On the other hand, clear reduction in K+/Na+ ratio in the flag leaves of both cultivars was observed. The capacity of osmotic adjustment was greater in younger leaves than in older ones particularly with higher concentration (25%) in both cultivars. Moreover, the production of both organic and inorganic ions tended to be higher in Sids-1 than in Gemmieza-9. Gemmieza-9 appeared to be more sensitive than Sids-1. Osmotic pressure of flag leaf sap appeared to depend mainly on proline, TSN, TSS, organic acids, glycerol and ions content, where there is a positive correlation between osmotic pressure and all of them.