The objective 3‘ the or sent study is to asses the effect of mineral and bio- nitrogen fertilizers or the nitra: content of cucumber fruits. Two field experiments were carried out a: Sakna A rlcultural Research Station Farm, Kafr El—Sheikh Governorate, Egypt uric; the two successive summer seasons of 2004 and 2005 using the recommended cucumber hybrid seeds. Split split plot design was used with four replicates The plot area was 20 squire meter. The main plots were assigned to two inoculation methods of ‘l- the inoculum was added as liquid and, 2- the lnoculum was added as tablets. The sub plots were assigned to three mineral nitrogen levels of 1- zero nitrogen (check treatment), 2- 30 kg N led"l (fed = 4200 m2), and 3- 60 kg N fed". The mineral nitrogen was added as ammonium nitrate 33%. The sub sub plots were assigned to two inoculation treatments of 1- without inoculation and 2- Inoculation with effective strains of non symbiotic Nz-fiXIf'lg bacteria. Nitrate content of the cucumber fruits was measured during the early. middle and late cuttings. The most important results can be summarized as follows: a Increasing mineral nitrogen levels led to dramatic increase of nitrate content in cucumber fruits and petioles in both seasons. o tear increases in nitrate content of cucumber fruits and petioles were detected due to inoculation with non symbiotic Ng—fixing bacteria in both seasons. o No clear differences in nitrate content of cucumber fruits and petioles were observed due to inoculation method-s in both seasons. t The highest nitrate content was observed in the samples from the early out and the lowest with the samples of late out in both seasons. +- Increasing the mineral nitrogen levels led to clear increases of nitrate and nitrite in the soil in both seasons. in Nitrate and nitrite in the soils were increased by the inoculation with non symbiotic Nz-fixing bacteria.