The effect of salinity stress on some parameters pertaining to the water relations of three important crop plants, flax (Linum usitatissimum), cotton (Gossypium barbadense) and wheat (Triticum aestivum) was studied. Such parameters investigated were: diurnal patterns of transpiration and relative water content of plants adjusted to different levels of soil osmotic water potential, 1J!s' using osmotica of NaCI and CaCl2 at a fixed sodium adsorption ratio (SAR) of l/S' Correlation analyses of obtained data revealed important facts: 1) Both temperature and VPD of air interfere in action with 1J!s in affecting transpiration, the interference magnitude is very high with cotton and not existant with wheat; 2) The osmotic potential of leaves may serve to maintain high relative water content, indicated by the significant positive correlation between both, in flax and cotton (not in wheat); 3) Soil osmotic water potential, 1J!s' induces significant reduction in transpiration rate, the reduction being dependant on evaporative power of air, especially in flax and cotton. The significance of the results obtained, in practical applications, is discussed.