Adrenomedullin (ADM) is found in male accessory sex glands and is part of the seminal secretion. It plays an important role in protecting the sperm in the female reproductive tract. In this study, we investigated the roles of ADM in inflammation and oxidative stress in the endometrium and in leukocyte and macrophage infiltration in the endometrial stroma. The expression of the ADM gene in the ventral prostate, coagulating gland, and seminal vesicle was determined by real time PCR. The peptide levels in the tissue and secretion were measured using an EIA Kit. The highest ADM mRNA and peptide levels were found in the ventral prostate. Most of the ADM in the seminal vesicle was stored in the tissue while little was secreted. The expression of the IL-1β gene and the secretion of TNFα and IL-6 in uterine tissue decreased significantly after treatment with ADM for 4 hours. Using an immunostaining method, the levels of leukocyte and macrophage infiltration were found to be lower at 24 hours post coitus than 1.5 hours post coitus. The infusion of ADM receptor antagonist reduced the infiltration of leukocyte and macrophages in the endometrial stroma at 24 hours post coitus. As to the anti-oxidative effect of ADM in the female tract, the reactive oxygen species (ROS) level in isolated endometrial epithelial cells was significantly decreased after treatment with ADM or seminal fluid. Our findings demonstrated that ADM in the seminal secretion may modify the inflammatory responses, play an anti-oxidative role, and increase leukocyte and macrophage infiltration in the uterus.