Total of sixty New Zealand White rabbits (NZW) of 5 weeks of age were used to study the effect of diazepam administration on some nutritional and physiological parameters in growing rabbits. Rabbits were divided into five treatment groups, each of 12 rabbits. The first group was the control, and the other four groups were administered (orally) with graded doses of diazepam (2.5; 5.0; 7.5 and 10.0 mg, respectively). Results obtained could be summarized as follows: 1-        Diazepam administration caused significant (P<0.05) increases in live body weight, weight gain, feed conversion ratio but decreased feed consumption 2-        Digestibility coefficients of (DM, OM, CP, EE, CF and NFE), nutritive values of (TND and DCP%); nitrogen balance and nitrogen retained as a percent of nitrogen intake increased significantly by diazepam administration. 3-        There were insignificant increases in both dressing percentage and hot carcass weight (%) in the drug treatment groups. 4-        Diazepam administration had no significant effect on plasma protein fractions, lipid fractions, however, slight increase in the plasma total lipids of treated animals were observed. 5-        There was no side effect of diazepam on liver function as observed from the GOT and GPT levels in the blood of treated animals. The same was also for kidney function where plasma urea and creatinine were insignificantly different. 6-        Diazepam administration inhibited thyroid function as indicated by the decreased rate of T4 conversion to T3. 7-        Plasma glucose level was significantly higher in the control group than treated groups. 8-        A significant increase in plasma phosphorus level was obtained but no changes in calcium level were observed. 9-        Blood packed cell volume and N/L ratio were not significantly different 10-     Diazepam increased the economic efficiency (%), and the performance index of the growing rabbits. It is suggested that diazepam administration may enhance the nutritive value and digestibility of diets and enhance the rabbits performance and can maintain a normal homeostasis for rabbits without any undesirable effects.