Two field experiments were performed at Sakha Agricultural Research Station, (31° 05' N latitude and 30° 56' E longitude), Kafr El-Sheikh Governorate, during the two growing summer seasons of 2009 and 2010, to study the effect of deficit irrigation by watering after 50%, 70% and 90% of available soil moisture deficit (ASMD) and four levels of nitrogen fertilization at 10, 20, 30 and 40 kg N fed.^-1 on cowpea yield, its components and water productivity in North Delta of Egypt. A split-plot design with four replicates was used. Mean values of seasonal water consumptive use were 42.17, 37.05 and 30.12cm in the 1^st season and 41.22, 36.51 and 29.67 cm  in the 2^nd season for the 50%, 70% and 90% of ASMD, respectively and seasonal amounts of irrigation water applied for cowpea were 63.10 cm, 54.09 cm and 43.10 cm in the 1^st season and 61.66, 53.33 and 42.40 cm  in the 2^nd season for 50%, 70% and 90% of ASMD, respectively. Results revealed that the highest values of plant height, number of leaves plant^-1, number of branches plant^-1 and chlorophyll content were obtained from irrigation at 50% of ASMD in the first season, while the highest values of seed yield plant^-1, seed yield fed.^-1 and number of  pods plant^-1 were obtained from irrigation at 70% of ASMD in the both seasons. The mean results showed that adding 40 kg N fed.^-1 significantly increased plant height, number of leaves plant^-1, number of branches plant^-1 and chlorophyll content in both seasons, while adding 30 kg N fed.^-1 gave the highest mean values of seed yield plant^-1, seed yield fed.^-1,number of pods plant^-1 and 100-seed weight in both seasons. The highest values of water productivity (WP) and productivity of irrigation water (PIW) were 0.763and 0.541kg m^-3  in the 1^st season and 0.568 and 0.403 kg of seeds m^{-3 in the 2nd} season as a result of irrigation at 90% of ASMD and fertilization with 30 kg N fed.^{-1 in the both seasons. Irrigation at 90% of ASMD enhanced WP by 29.7 and 33.4%  and PIW by 35.9 and 39.7% compared to irrigation at 50% of ASMD in the two seasons, respectively. WP and PIW increased by increasing N application up to 30 kg N fed.-1}. It can be recommended that the best results under the experimental conditions were irrigating cowpea cultivars at 70% of ASMD and fertilization with 30 kg N fed.^-1.