This study was conducted to investigate the influence of using discarded date as a source of energy to replace of 25, 50 and 75% instead of barely grains in growing New Zealand rabbit diets on growing rabbit performance. A total number of 48 unsexed, weaned New Zealand White rabbits of 6 weeks old were randomly divided into four experimental groups (12 for each). Four pelleted experimental diets were formulated to be approximately isocaloric, isonitrogenous and isofibrous. The trail lasted about 8 weeks and experimental group animals were allotted to receive four experimental diets. Insignificant (P≥0.05) differences were observed in feed consumption among the different experimental groups. Using of 25 and 50% discarded date in growing rabbit diets increased significantly live body and daily weight gain. Feed conversion ratio was significantly improved with feeding 25 and 50% discarded date compared to control diet. Replacing 25 % of the barely by discarded date significantly increased the values of DM, CP, CF digestibilities and percentages of TDN, DE and NB compared to the other groups. Also using 50% discarded date as replacer to barely significantly increased the values of DM and CF digestibility than the other groups. Discarded dates at levels 25% in the diets, led to significant differences in empty carcass and dressing percentage% compared to the control groups. Using 75% discarded date as replacer to barely significant increase the values of catalase than the other groups. Data showed significantly decreased in the value of lipid peroxidase for rabbits fed on diets containing of discarded dates at levels 50 and 75% compared to the control groups. Analysis of variance revealed that using 25 or 50% discarded dates as instead to barely significantly increased the value of total volatile fatty acid and ammonia concentration compared to the control group. Discarded dates at levels 25 and 50% led to significant differences in triiodothyronine hormone (T₃) compared to control group.  Using 25, 50 and 75% discarded dates as a source of energy in growing rabbit diets decrease feed cost and improve economic efficiency. In general, the results indicated that using discarded dates in rabbit diets with rate of 75% of barely grains reduced fed costs without adverse effects on performance of rabbits.