A field trial was conducted at Giza Agricultural Research Station during the two successive seasons 2009/2010 and 2010/2011 to study the response of barley to different irrigation regimes induced due to irrigating according to 1.1 (wet irrigation regime), 0.9 (medium irrigation regime) and 0.7(dry irrigation regime) coefficients for the accumulative pan evaporation (APE) records in combination with nitrogen fertilization rates of 0, 15, 30 and 45 kg Nfed^-1. Results of combined analysis could be summarized as follows:- 1. The assessed irrigation regimes had a significant effect on plant height, spike length, number of spikes m^-2, number of grains spike^-1, 1000 kernels weight, biological yield fed^-1., harvest index, grain and straw yields. The highest values of such characters were obtained for wet irrigation regime (1.1 APE) followed by medium (0.9 APE) and dry (0.7APE) ones, respectively. Protein content of barley grains increased as plants were imposed to severe water stress (dry irrigation regime, 0.7 APE). 2. Seasonal water consumptive use (WCU) was increased under wet irrigation regime (1.1 APE coefficient). Whereas, water use efficiency (WUE) increased under medium irrigation regime (0.9 APE coefficient). 3. Appling 45 kg N fed^-1 significantly increased plant height, spike length, number of spikes m^-2, number of grains spike^-1, 1000 kernels weight, biological yield, harvest index, grain and straw yields. Furthermore, protein content of grains, seasonal water consumptive use (WCU) and water use efficiency (WUE) tended to increase due to the highest N- rate. 4. The interaction effect between irrigation regimes and nitrogen fertilization rates was found to be significant for growth, yield and its components characters. The maximum values of plant height, spike length, number of spikes m^-2, number of grains spike^-1, 1000- kernel weight, biological yield, harvest index, grain and straw yields were obtained as barley irrigated at 1.1 APE coefficient under 45 kg N fed^-1 rate. Higher water consumptive use (WCU) values resulted from interaction of wet irrigation regime (1.1APE) and 45 kg N fed^-1 rate. Whereas, the highest values of water use efficiency (WUE) were recorded as barley plants were irrigated at medium irrigation regime (0.9 APE) under 45 kg N fed^-1. The maximum values of protein content in barley grains were obtained due to irrigating at the dry irrigation regime (0.7 APE) in combination with 45 kg Nfed^-1 rate.