The objective of this study was to evaluate the uterine microbiota composition of cows on day 15 of the estrous cycle. Non-pregnant Bos taurus beef cows (n = 23) were exposed to an estrus synchronization protocol to exogenously induce synchronized ovulation. Transrectal ultrasonography was performed to evaluate ovarian structures, ensure synchrony, and determine the side of ovulation. Cows were harvested on day 15 of the estrous cycle and individual swabs were collected from each uterine horn using aseptic techniques. DNA was extracted and the entire (V1-V9 hypervariable regions) 16s rRNA gene was sequenced. Sequences were analyzed using the QIIME2 Pipeline. The composition of the microbial community on day 15 of the estrous cycle differed between the ipsilateral and contralateral horn of cows, and between cows that expressed estrus and cows that failed to express estrus.