Two field experiments were conducted at the Experimental Farm of Sakha Agric. Res. Station during the two successive seasons 2006/2007 and 2007/2008. The aim of this work is to study the influence of irrigation intervals (traditional, irrigation at 60 %depletion of available soil moisture and irrigation at 100 and  80 % of cumulative pan evaporation) and applied irrigation water at  flow rates (30 and 60 L/sec) on productivity of flax and some irrigation efficiencies. The design of the experiments were split-plot design. The obtained results could be summarized as follows:                 Seed yield and other plant parameters such as plant height, , capsules number per plant and protein content had significantly affected  with various irrigation treatments. Irrigation at 100%, 80% from cumulative pan evaporation and 50%depletion of available soil moisture were superior to traditional treatment, respectively. Irrigation at 100 %  pan evaporation recorded the highest values of  flax seed yield (540.8 and 539.4 kg/fed.), straw yield(3.545and3.767ton/fed.),plant height(114.9 and 116.2cm), technical length (101.8 and 100.5cm)and capsules number per plant(13.93and14.89)in the first and second seasons, respectively Irrigation of flax plants at 60 % depletion of available soil moisture  resulted in the highest oil content (41.98 and 40.4 %) in the first and second seasons, respectively. Irrigation at high flow rate( 60 L/sec) increased values of plant height, technical length, number of capsules per plant, seed yield, straw yield, oil and protein contents compared to low flow rate (30L/ Sec.)in the two growing seasons. ● The interaction between irrigation intervals and flow rate (I x F) had significant effects on the technical length in the 1st season, while in the2^nd season, the interaction had a significant effect on all parameters except seeds yield and protein content. - The lowest values of water applied (1914.83 and 1967.6m³ /fed.) were found under irrigation at 100 %  pan evaporation , while the highest values of water applied  (2463.5and 2530.5 m³/fed.) were recorded with traditional irrigation in the 1^st and 2^nd seasons, respectively. - The amount of water applied (2266.23 and 2334.2m³/fed.) with flow rate of 30 L/sec. was higher than that 2087.9 and 2140.1m³/fed. with flow rate of 60 L/sec in the 1^st and 2^nd seasons, respectively. - Water consumptive use (m³/fed) generally behaved the same trend of water applied for all treatments. - Water application efficiency values were higher with treatments which irrigated at 100% and 80% from cumulative pan evaporation and 60%depletion from available water than traditional treatment. Also, the values were increased with increasing flow rate. Irrigation losses had almost the opposite trend to that  encountered with water application efficiency. - The highest average values of CWUE and FWUE were recorded under irrigation at 100 % pan evaporation and flow rate of 60 L/sec. in the two growing seasons. - Irrigation at 80 % from cumulative pan evaporation achieved the highest value of water application efficiency (77.00 and 76.91%) in the 1^st and 2^nd seasons, respectively.             It can be recommended to use evaporation pan class A in irrigation scheduling (proper time and amount of water) to maximize the return from unit of water applied and save irrigation water.