A two field experiment was conducted 2004l2005 and 2005(2006 seasons at Etay El-Baroud Agric. Res. Station to study the effect of sewing and harvesting date on yield and yield components of some flax varieties. In each season, five flax varieties, viz: G'rzaB, Sakha‘l, Sakhaz, Sakhaa, and Sakha4, three sowing dates viz: 30(10, 15111, and 1i12, and three harvestingdates viz: 135, 150, and 165 days after sowing were evaluated in split—split plot design with four replicates. The main results obtained from this study showed that varieties differed significantly in straw and seed characters under study. Sakha3 was superior to other varieties in technical length, straw yield per faddan, fiber length and fiber percentage. While Gizafl superior to other varieties in main stem diameter. On the other hand Sakha2 was superior in straw yield per plant. seed yield per plant as well as faddan, number of capsules per plant, number of seed per plant, moo-seed weight (seed index) and oil percentage. Sowing date had a significant effect on all characters, excr pt main stem diameter, woo-seed weight and oil percentage. Sowing flax on 15Ith Nov. recorded the highest means of straw and seed yields as well as its components. Harvesting date significantly affected all studied characters, except main stern diameter. The proper time for harvesting flax markedly depended on sowing on 15"" Nov. and harvesting at 150 days which was the suitable date to produce the highest straw yield, while sowing on 15"h Nov and harvesting at 165 days after sowing was the suitable time to produce the highest seed yield.