Exposure of the female genital tract to seminal fluid elicits robust cellular and molecular changes which have been shown in mice to prepare the female immune response for embryo implantation and an ensuing pregnancy, through establishing regulatory T cell tolerance. Seminal fluid contains abundant signaling agents, with the three mammalian isoforms of TGFB identified as key mediators of the post-copulatory immune response in mice and humans. Interferon-g (IFNG), a potent inducer of adaptive immunity, is generally present at low levels in human seminal plasma but can be elevated in response to infection and/or inflammation within the male genital tract. Elevated seminal fluid IFNG content has been linked with idiopathic infertility, independently of sperm parameters, consistent with IFNG having the potential to adversely affect female immune priming. In this study we investigated the effect of IFNG on the response to seminal fluid, using the ectocervical epithelial (Ect1) cell and primary ectocervical epithelial cell in vitro models of seminal fluid signaling. IFNG added at 50pg/ml or 5ng/ml suppressed the capacity of seminal plasma (n=3) to elicit synthesis of the key pro-tolerance cytokine colony-stimulating factor 2 (CSF2) from Ect1 cells. IFNG was found to suppress CSF2 induction by TGFB in a dose-dependent manner, at both the protein and mRNA expression level in both Ect1 cells and primary cells. Conversely, TGFB counteracted the impact of IFNG and inhibited IFNG receptor gene expression in a dose-dependent manner. Additionally, seminal plasma samples identified as containing IFNG (>10 pg/ml) induced a 50% lower CSF2 response in Ect1 cells, compared with samples containing <3 pg/ml IFNG (n=5 per group). These data identify IFNG as a potent inhibitor of TGFB-mediated seminal fluid signaling in cervical epithelial cells, and raise the prospect that the male partner’s seminal fluid IFNG content may be a determinant of fertility acting at coitus in women.