A pot experiments were carried out during two successive seasons of 200312004 and 2004i2005 at the Experimental Station of Medicinal and Aromatic Plants, Fac. of Agric., Mansoura Univ., to study the effect of different salinity level of diluted sea water (2.5, 5 and 10%), which were equivalent to the application of 825, 1650 and 3300 ppm, respectively on growth, oil content, oil components and chemical composition of rosemary (Rosemarinus officinaiis. L.). Whereas control plants were irrigated with tap water. The results showed that increasing salinity levels reduced all growth traits (plant height, number of branchesiplant, herbage fresh and dry weights) compared to the control. All saline water treatments decreased the content of chlorophylls a and b, oil percentage and essential oil yieldiplant, as well as K percentage and K: Na ratio in herb, during the cuts harvested, in both seasons. Reducing, non-reducing and total soluble sugars (“/u), free proline content (moleig F.W.) and Na and Cl percentages in herb showed opposite trend. Gas liquid chromatography analysis of samples revealed seventh identified compounds. Salinity had a clear effect on the chemical composition of the extracted rosemary oil, since some of the major constituents increased such as c-Terpinene, Cineole, Linalool and Bornaol. While, P-cymene and Thymol decreased with the higher salinity levels. Anatomically, salinity decreased stem diameter, cortex thickness, phloem, xylem and pith tissues thickness. Width of cambial zone were also decreased. Moreover, salinity decreased leaf thickness, palisade and spongy tissues thickness, midvein vascular bundle dimension as well as xylem and phloem tissues thickness.