Two field experiments were carried out at El-Gemmeiza and Sakha Agriculture Research Stations, Gharbia and Kafr El-Sheikh Governorates, Egypt in 2016/2017 and 2017/2018 seasons to study the effect of three nitrogen fertilizer rates (30, 45 and 60 kg/feddan)on four flax varieties(Giza 11,Giza 12, Sakha 5 and Sakha 6) .Results indicated that, fertilized flax Giza 12  variety with nitrogen fertilizer at the  rate of 45 kg N /feddan at El-Gemmeiza  location yielded the highest values of seed index, seed yield per plant, seed yield per feddan, and oil yield per feddan,  on the same line fertilized flax Giza 12  variety with nitrogen fertilizer at the rate of 60 kg N /feddan at El-Gemmeiza location  produced the highest values of plant height, fiber length, straw yield per plant, straw yield per feddan and fiber  yield per feddan. On the other hand, flax Sakha 6  variety with nitrogen fertilizer at a rate of 60 kg N /feddan at El-Gemmeiza  location gave the highest values of number of capsules per plant but flax Sakha 5 variety with nitrogen fertilizer at a rate of 45 kg N /feddan at Sakha  location gave the highest values of oil percentage  only as compared with all other this interaction treatments in 2016/2017 and 2017/2018 seasons , respectively .