Benefits of dietary lipid supplementation during transition period have been shown to improve reproductive performance in dairy cows (Mattos et al., 2004; Thatcher et al., 2006). However, effect of different oil sources on reproduction has not been consistent (Funston, 2004). Thus, the objective was to examine effects of sunflower (SO) and palm oil (PO) supplements in diet on early embryonic development, luteal size and blood flow area, PGF_2α metabolite (PGFM), and progesterone (P4) concentrations. Prepartum cows (n = 42) were randomly assigned into one of 3 dietary treatments (control, 4% PO, and 4% SO supplements). Animals were fed diets individually from d 28 prepartum to d 111 postpartum. Cows were synchronized estrus with 2 injections of PGF_2α given 11 d apart. Blood samples were taken from d 5 until d 35 postpartum and throughout the estrous cycle (d 3, 5, 7, 9, 11, 13, 15, 17 and 19) for PGFM and P4 analyses, respectively. Luteal size and blood flow area were determined throughout the estrous cycle by Doppler ultrasonography. Oocytes were collected in 3 ovum pick-up sessions at 2-wk intervals for the in vitro embryo production starting on d 83 postpartum. Total DMI and milk yield were greater (P < 0.05) in cows fed plant oil supplements than control group during 35 d postpartum. Oocyte characteristics and embryonic development were not affected by dietary treatments. Cows fed 4% SO had greater (P < 0.05) concentration of PGFM from d 15 to d 35 postpartum than those cows fed 4% PO and control group. On the mid-luteal phase (d 11 of the estrous cycle), serum P4 concentrations (6.0 ± 0.7, 5.7 ± 0.5, and 4.7 ± 0.6 ng/mL), luteal size (7.0 ± 0.2, 6.5 ± 0.2, and 5.3 ± 0.1 cm²) and luteal blood flow area (1.3 ± 0.2, 1.2 ± 0.1, and 0.9 ± 0.1 cm²) were greater (P < 0.05) in cows fed 4% SO and 4% PO than control group, respectively. Thus, plant oil supplements in diet affected luteal size and serum P4 and PGFM concentrations, but not early embryonic development. Such changes in secretion of PGF_2α and P4 indicate that plant oil supplements during pre- and postpartum may alter uterine and luteal functions.