The objective was to characterize effects of Escherichia coli LPS (given iv) on corpus luteum (CL) and embryonic viability in early pregnant cattle. Eight non-lactating German Holstein cows were given 0.5 µg/kg LPS on 35 ± 3 d (mean ± SEM) of pregnancy, whereas seven heifers, 41 ± 6 d pregnant, were given 10 ml saline (Control group). Transrectal B-mode examinations of the CL were done at -1, 3, 6, 12, 24, 48, 72, and 96 h relative to treatment. Blood samples were collected at -1, 0.5, 1, 2, 3, 4, 6, 9, 12, 24, 48, 72, and 96 h. At 12 and 48 h, the CL was biopsied. None of the cows still in the experiment 10 d after LPS (n=7) had embryonic loss. In LPS-treated cows, luteal area decreased (from 4.1 to 3.1 cm2; P≤0.05) within 6 h and until 48 h. Luteal blood flow decreased by 39% (P≤0.05) within the first 6 h after LPS, but returned to pre-treatment values by 48 h. Plasma P4 decreased by 62% (P≤0.05), reached a nadir (2.7±0.6 ng/mL) at 12 h after LPS and was not restored to pre-treatment (P≤0.05). In luteal tissue, mRNAs for StAR and for FGF1 were lower (P≤0.05) in LPS- than in saline-treated cattle at 12 h, with no difference between groups at 48 h. Levels of mRNAs for Casp3 and FGF2 were not different between groups (P>0.05) at 12 or 48 h after treatment. In conclusion, LPS transiently suppressed CL function, but did not induce embryonic mortality.