A lactation study was conducted to assess productive and reproductive performance of Friesian dairy cows supplemented with raw safflower (R-SAF) or sunflower seeds (R-SUN) and identify its impact on ruminal fermentation, lactational performance, milk fatty acid (FA) profiles and reproductive performance. Fifteen primiparous and multiparous Friesian dairy cows were grouped according to predicted calving date, parity, body weight and previous milk yield for multiparous cows. Cows were randomly assigned equally to one of three treatments: (a) control, (b) R-SAF or (c) R-SUN for 90 days (treatment period, TP). The TP started at approximately 30 ± 5 days prior to their expected calving date and continued until 60 days after calving. Supplemental seeds were added at 3.36% and 3% of dietary DM during prepartum and postpartum periods, respectively. Feed intake was nearly similar among treatments in late gestation or early lactating periods. Digestibility of all nutrients of rations containing R-SAF or R-SUN were significantly (P<0.05) increased compared to control. The pH value and NH3-N concentration were significantly (P<0.05) decreased, while total volatile fatty acids (TVFA´s) concentration was increased significantly (P<0.05) with R-SAF or R-SUN groups compared to control. Serum total protein, albumin and Urea-N concentrations were increased significantly (P<0.05) by supplementation of safflower or sunflower seeds to the lactating cow's ration (R-SAF or R-SUN) compared to control. Globulin concentration was not affected by the fat supplementation. The AST and ALT activities were not affected significantly by the use of R-SAF or R-SUN rations compared to control. Feed conversion as DM, TDN and DCP/kg FCM improved of lactating cows fed R-SAF or R-SUN rations compared to control. Milk yield and its composition of lactating cows fed R-SAF or R-SUN rations were significantly (P<0.05) increased compared to control. Palmitic acid (C16:0) concentration in the milk fat was elevated by feeding the R-SAF or R-SUN rations compared to control. The same trend of C16:0 was obtained with C18:0, C18:1 ω 5, 7, 9, C18:2 ω 6, C20:0 and C20:4. Superior the reproductive performance of cows fed rations supplemented with R-SAF or R-SUN compared to non-treated ones. In conclusion, supplementing rations of Friesian dairy cows with R-SAF or R-SUN at 3% of dietary DM can be an effective strategy of fat supplementation to lactating dairy cows with positive effects on lactational performance, milk FA profiles and reproductive performance. In addition, functional quality of milk was enhanced by increased conjugated linoleic acid (CLA) concentration and additional benefit to human health.