This study was conducted at the Experimental Farm, Fac. Environ. Agric. Sci., El-Arish at North Sinai Governorate, Egypt during the period from May 2014/ May 2016 to study the effect of some irrigation treatments on vegetative growth and chemical composition of Casuarina equistefolia Seedlings. Seedlings were planted and two types of water were used (wells water and treated waste water to irrigate at the following rates (wells water 100% - wells water 75%: 25% treated waste water - 50% wells water: 50% treated waste water - wells water 25% : 75% treated waste water - 100% treated waste water). Three irrigation intervals were used for each of the previous five treatments every one, two and three weeks. In each treatment the following measurements were taken i.e. plant height, number of main shoots, the main stem diameter. These measurements were taken every three months over a full 2 seasons (24 months).At the end of the experiment leaves were taken from Casuarina to determint N, P and K. Results of these study revealed that irrigation with 100% treated waste water (T.W.W) increased the growth and chemical composition (N, P and K) of Casuarina equistefolia Seedlings compared with others Types water. These findings suggested that, dependence on treated waste water mainly in irrigation of wood trees and makes it a major source to produce some kinds like Casuarina.