This study was carried out on Mentha longifolia L. Fam. Lamiaceae (Labiatae) at the Farm of North Sinai Research Station, El-Sheikh Zwaid city during the two successive seasons of 2014/2015 and 2015/2016 to improve growth, productivity and oil production as well as chemical composition of Mentha longifolia L. plant under North Sinai conditions by using humic acid (0, 3 and 6 Litre.fed^-1) under different levels of saline water (Tap water, 2048 ppm and 4224 ppm). Generally the highest values of vegetative growth parameters, oil production and chemical composition were obtained by using tap water and fertilizing with humic acid at 6 l.fed^-1 in first experiment. But under arid and semi-arid conditions like North Sinai Governorate, humic acid could offer an economical and simple application to salt sensitive plant, it can be use saline water at 2048 ppm + humic acid at 6 l.fed^-1 to decrease water salinity stress without decreasing in yield or oil production of Mentha longifolia L.