The bacterial cell wall component lipopolysaccharide (LPS), depletes primordial follicles in ex vivo cultured bovine ovarian cortical strips and in exposed mice. LPS also affects mRNA encoding anterior pituitary hormones. Many studies have characterized negative ovarian effects of acute (bolus) LPS exposure. Our objective was to characterize the effects of chronic endotoxemia on follicular development in lactating cows. To create a more physiologically relevant LPS exposure paradigm, cows were continuously intravenously (i.v.) infused with LPS for 7d. Eleven lactating Holstein cows (164 ± 22 DIM; 676 ± 16 kg BW; parity 3.1 ± 0.4) were acclimated for 3d, and enrolled in 2 experimental periods (P); during P1 (3d) cows consumed feed ad-libitum and baseline serum samples were obtained. During P2 (7d), cows were assigned to either treatment 1) saline-infused and pair-fed (CON-PF; 40 mL/h saline; n = 5) or 2) LPS-infused and ad libitum-fed (LPS-AL; E. coli O55:B5; 0.017, 0.020, 0.026, 0.036, 0.055, 0.088, and 0.148 μg/kg BW/h for d 1–7, respectively; n = 6). CON-PF cows were pair-fed to LPS-AL group to create uniform nutritional status. Estrous cycles were synchronized using a modified Ovsynch protocol before the experiment such that ovulation from the previous estrous cycle occurred on P1D2 and the first wave of follicular growth was monitored using trans-rectal ultrasonography every 24h. Dominant follicles increased in size in CON-PF (33%) and LPS-AL (30%) ovaries between d 4 and d 7 post-induction of ovulation, with no impact (P > 0.05) of LPS on either growth rate or size of the dominant follicle on d 7. LPS did not affect (P > 0.05) concentration of progesterone in serum or follicular fluid or serum 17β-estradiol. There was a trend for increased 17β-estradiol in serum (44%; P = 0.1) in LPS-AL cows. These data do not rule out potential LPS effects on the ovarian follicular reserve, however, demonstrate the surprising capacity of lactating dairy cows to tolerate exponentially increasing chronic LPS exposure without disrupting dominant follicle growth. Interestingly, there is potentially greater circulating 17β-estradiol in LPS-exposed cows, without any impact on progesterone abundance. Supported by Land-O-Lakes fellowship to MJD.