This investigation was carried out during the two seasons 1999 and 2000 on Damsisa plant in Medicinal and Aromatic Plants Research Department, Sabahia Station, Alexandria to study the effect of saline irrigation water and plant spacing on growth, volatile oil percentage and composition in leaves, demsine as well as ambrosine and total demsine and ambrosine.                 Application of saline irrigation water (4000 and 8000 ppm) significantly increased plant growth and volatile oil percentage in leaves while, it was decreased with the high level (12000 ppm).                 Plant spacing (35 cm) with low levels of saline irrigation water (4000and 8000 ppm) gave the highest values of plant growth, volatile oil percentage and compositions.                 Ambrosine percentage increased by increasing saline irrigation water levels with plant spacing, oppositely, demsine and total (demsine and ambrosine) percentage were decreased.