Aim of the current study was to investigate the effects of feeding small ruminants on diets contained date palm tree leaves (DPL) incubated or not with enzymes. Biological treatments were used in laboratory experiment to determine the effect of using different enzymes (Cellulase, Taninnase, Fibrolytic and combinations of each with other) on chemical composition of date palm leaves. In vitro trail was conducted using diets contained 40% DPL incubated with enzymes to study in vitronutrients disappearance. A digestibility trails were carried out to study digestibility coefficients, nutritive values, nitrogen balance, rumen fermentations and microbes and some blood components as follow: D (1): 50 % concentrate feed mixture (CFM) + 50% berseem hay (BH) (control diet). D (2): 50 % CFM + 40% DPL +10% BH.D (3): 50 % CFM +40% DPL incubated with Cellulase enzyme +10% BH. D (4): 50 % CFM +40% DPL incubated with Fibrolytic enzyme +10% BH. D (5): 50 % CFM +40% DPL incubated with Cellulase and fibrolytic enzymes. Results showed that enzymes improved chemical composition of DPL, CP content was increased while CF and its fractions were decreased (P≤0.01). The incubation of DPL in diets with enzymes improved nutrients disappearance. Digestibility coefficients, nutritive values and nitrogen balance showed significant increase(P≤0.01) with diets contained enzymatic DPL. The highest improvement of rumen fermentations and microbes were reported with DPL contained enzymes compared to control and non- enzymatic DPL. Serum total proteins and albumin concentrations were increased significantly (P≤0.01), while urea concentration was decreased with diets contained enzymatic DPL.