Abstract: The effects of exogenously applied glycinebetaine or ascorbic acid (pre-soaking or pre-soaking plus spraying) on the salt-stress induced ultrastructural damages in sweet pepper seedlings were investigated. The seedlings grown in hydroponic culture containing nutrient solution for 4 weeks treated with NaCl at (0 and 6000 ppm). Salinity induced ultrastructural damages in leaf, the most notable changes were swelling of thylakoid membrane, disintegration of grana stacking and intergrana lamellae and showed a wavy configuration, increase the number of plastoglobuli and starch grains (number and size), mitochondria swelling, the number of mitochondria cristae was decreased (absent or often very short) and the cristae were observed only on one side of the bowl, but on the other side consisted of two membranes of the envelope and separated by a thin matrix layer. Moreover, the thickness of cell wall and the vacuolar volume or sizes were also increased as well as formation of the Myelin-Figures from plasma membrane. These damages were alleviated by the pretreatment with glycinebetaine or ascorbic acid (pre-soaking or pre-soaking plus spraying) at certain concentrations.