Purpose of this study was to evaluate the effect of replacing alfalfa hay with date palm tree leaves (DPL) untreated or treated with urea in diets and study its effect on sheep feeding. The effect of using urea with different levels (4, 6 and 8%) on chemical composition and fiber constituents of date palm leaves was studied in laboratory experiment; also, four rations included different ratios of date palm leaves  (15, 25, 35 and 50%) were carried out to choose two of them. Then the chosen two ratios of DPL were used to study the effect of the three levels of urea on the chemical composition and in vitronutrients disappearance of these ratios. Then the perfect ratio of DPL treated with different urea levels used to study its effect on sheep performance, the rations were: C: ration contains 50% CFM + 50% berseem hay BH (control). R (1): control replaced by 35% DPL. R (2): control replaced by 35% untreated DPL (4% urea). R (3): control replaced by 35% DPL (6% urea) and R (4): control replaced by 35% DPL (8% urea). Main results indicated that urea treatment improved chemical composition of DPL compared with untreated as CP content increased while CF and its fractions decreased (P≤0.01). The enhancement in CP, CF, cellulose and hemicellulose contents and the improvement of nutrients disappearance for rations contained 35% DPL treated with urea (4, 6 and 8%) suggested using these rations in digestibility trial which indicated significant increase (P≤0.01) for digestibility coefficients, nutritive values, nitrogen balance and rumen fermentations and microbes compared to untreated ration. Also, treated rations significantly (P≤0.01) enhanced serum total proteins and albumin concentrations more than control and untreated rations, although they increased urea concentration.