A field study was carried to determine the effect of saline irrigation on growth and mineral composition of Prosopis juliflora and Acacia arabica in an arid environment of Saudi Arabia. Four irrigation waters with salinity levels of 2000, 8000, 12000 and 16000 total dissolved solids (TDS, mg L-1) were used in the study. Mean biomass yield of shoots and roots of both trees increased significantly with increasing irrigation water salinity. Mean concentration of protein, Ca and Na increased while that of P, K and Mg decreased with increasing irrigation water salinity. Irrigation with high salinity water also caused significant increase in soil salinity.The study proved the sequence for salt tolerance as Acacia arabica >Prosopis juliflora. Overall, the study showed the potential of developing range lands by growing these two trees using saline irrigation water.