Two field experiments were carried out at El-Gemmeiza Research Station, Gharbia Governorate, Agricultural Research Center, Egypt, during the two successive winter seasons of 2015/2016 and 2016/2017. The objective of this work was to evaluate the effect of irrigation intervals (every 21, 28 and 35 days) and nitrogen fertilizer rates [control (0), 30, 45 and 60 kg N/fad] on quantity and quality of straw and seed characters of flax (Variety Giza 10). The experimental design was split plot with three replications.   The obtained results can be summarized as follows:- Obtained results indicate that significant differences in all studied traits among irrigation intervals in both seasons and combined analysis. Irrigated flax plants every 21 days gave the maximum values for plant height, technical length, straw yield/fad, fiber yield/fad, number of capsules/plant, number of seeds/capsule, seed yield/fad and oil yield/fad as well as gave the minimum values of fiber fineness (Nm). In contrast, irrigation every 35 days gave the minimum values for all studied characters under this study except, fiber fineness (Nm). Irrigated flax every 28 days gain intermediate estimates in all studied traits without significance with irrigation every 21days. All traits of flax under study, i.e. plant height, technical length, straw yield/fad, fiber yield/fad, number of capsules/plant, number of seeds/capsule, seed yield/fad and oil yield/fad showed significantly increased by increasing nitrogen fertilizer rates from 0 up to 60 kg N/fad, except fiber fineness (Nm) which decreased with increasing nitrogen rates in the both seasons and combined analysis. Results showed that irrigated flax plants every 21 days and soil fertilized with 60 kg N/fad gave the maximum values of plant height and straw yield/fad only in the second season as well as seed and oil yields/fad in the two seasons and the combined. In addition to great reduction in fiber fineness had happened in this case. It could be summarized that irrigated flax plants (Giza 10) every 21 or 28 days and soil fertilized with 60 kg N/fad to maximized quantity and quality of straw and seed yield characters.