In vivo and in vitro studies showed that E. coli LPS and BoHV4 often cooperate to induce endometritis. In this study, we used an in vitro model to characterize their effects on proliferation and death of bovine endometrial epithelial cells (EC). Bovine uteri from luteal phase cows (CL histology) were collected from slaughterhouse and EC primary culture established. EC from 9 cows, on passages 4 to 6 were challenged with 0(Control, C) 2, 4, 8, 12, or 16 µg/ml LPS. The numbers of attached cells were counted 72 h later. Variation in cell number (%) = (number of LPS treated-number C)/number C, was analyzed by ANOVA (SAS 9.1, PROCGLM, 3classes of cells number (<5, 5-10, >10 x 105), 5 classes of LPS. EC from 2 cows were exposed for 5 days to dilutions (10-6 to 10-1) of one BoHV4 strain and the variation in cell number analyzed. LPS strongly stimulated proliferation of endometrial epithelial cells without increasing cell death. LPS effect was dose dependent but not in a linear manner; the maximum stimulation (+20% to 40%) being observed for the 8 µg/ml dosage (p < 0.0001). Exposure of EC to BoHV4 induced cell death, the LD50 being observed for the 10-4 to 10"3 dilutions and no or <1% cells remained alive for the 10-1 dilution. These preliminary results confirm the pathogenic effects of this BoHV4 strain and the proliferative effects of LPS observed for other types of EC. This system will be used to optimize the challenges with BoHV4 and to further study molecular changes induced by LPS and BoHV4.