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The responses of CO2 uptake, transpiration and stornatal conductance from two wheat cultivars, Known to be tolerant (Sholeh) and intolerant (Inia-66), grown in saline conditions (0, 2.5 and 5 g/l NaCl) were measured using Infra Red Gas Analyser, in a split plot design . The results showed that with Sholeh the CO2 uptake was reduced only at the highest level of salinity used. Parallel reductions to CO2 uptake in transpiration and stomatal conductance in both cultivars indicate that in saline conditions the stomatal resistance to CO2 may greatly cause reductions in Photosynthesis. Microscopic observations on leaf tissues showed that CO2 flux may partly be limited by alterations in leaf internal structure.