Water stress is the main abiotic stress that negatively affects crop production. A field investigation was conducted at Sakha Agricultural Research Station during 2018/ 2019 and 2019 / 2020 winter seasons to evaluate the response of five flax cultivars (Sakha 3,Sakha 5,Sakha 6,Giza 11and Giza 12)under three irrigation treatments i.e. three irrigations after sowing irrigation (control treatment), Skipping the  3rd irrigation after sowing irrigation (irrig. 1 treatment) and Skipping 2nd and 3rd irrigation after sowing irrigation (irrig. 2 treatment). A split plot design with four  replicates was used in this experiment.  Results indicated that chlorophyll a , chlorophyll b , relative water content and proline, were not significalty affected with decreasing number of irrigations to two irrigations after sowing irrigation (irrig1 treatment), while malondialdehyde(MDA)and No.of capsules plant^-1were affected significantly. On the other hand irrig2 treatment badly affected all physiological studied characteristics and led to a significant decrease in straw and seed yields of all cultivars under study. It could be recommended with sowing Giza 11or Giza 12 and skipping the third irrigation after sowing irrigation to obtaine a high seed and straw yield with saving irrigation water as well as  obtaining the highest productivity of irrigation water for both seed and straw yields (PIWseed and PIW straw).