This study was performed to evaluate the effect of feeding two levels of omega 6 to omega 3 (1:15 and 1: 4) during the transition period on milk production performance, blood parameters and some reproductive traits of high-producing Holstein cows. In the experimental diets, calcified flaxseed oil was used as a source of omega-3 and calcified soybean oil was used as a source of omega-6. In this experiment, 24 Holstein dairy cows were used in a completely randomized design, so that at the start of closw-up stage the cows were divided to two groups (n=12) : group received diet with high omega 6 to omega 3 ratio (1: 15, H) and group recived diet with low omega 6 to omega 3 ratio (1: 4, L). After calving, each group of cows was devided to two groups (n=6): groups recived diet with high omega 6 to omega 3 ratio (15:1, H) and group revieved diet with low omega 6 to omega 3 ratio (1: 4, L). The rations at each stage were isocaloric ad isonitrogenus. Cows were kept in indivitual pens and feed was distributed two timesin the morning (08:00) and in afternoon (16:00). The results showed that pre- and postpartum feed intake was not affected by the experimental diets. Production of milk, lactose and solids non fat od milk in cows consuming HL diet, and fat percentage and fat to milk protein ratio in cows consuming LL diet was higher (P 0.05) than those the other groups. Changes in body condition score and fertility traits did not affect by the treatments (P 0.05). Glucose, cholesterol, triglyceride, BHBA, NEFA, albumin, protein and alanine aminotransferase (ALT) were not affected by the experimental treatments. Hepatic enzyme, aspartate aminotransferase (AST) was higher (P 0.05) in cows fed LL and HL diets than the two other gorups. In general, it can be concluded that useing calcifiedsoybean oil as a source of omega 6 in the close-up ration and useing calcifiedflaxseed oil as a source of omega 3 in the fresh ration may have positive effects on transition dairy cow performance. Keywords: transition period, soybean oil, flaxseed oil, omega-6 to omega-3 ratio, milk production.