Insulin signalling is mediated by a complex, highly integrated network that controls several processes including glucose homeostasis, protein synthesis and cell growth. Traditional paradigms hold that insulin production is restricted to the beta cells of the pancreas. However, this long held view of insulin genesis has been challenged by recent studies showing that insulin can be produced by alternative, non-pancreatic cells. For instance, insulin has been detected in porcine spermatozoa and been shown to be released from ejaculated human spermatozoa in response to glucose. Furthermore, insulin has been shown to be beneficial to spermatozoa, with the capacity to act as a pro-survival factor, improve their motility characteristics, and enhance their ability to complete an acrosome reaction. This study addresses the possibility that insulin might also be secreted by the endometrium in order to sustain spermatozoa on their extensive journey from the site of insemination to the ampullae of the Fallopian tubes where fertilization takes place. Our preliminary experiments using nested PCR, indicated that insulin mRNA was indeed present in the murine uterus. We have since confirmed these data using immunocytochemistry targeting the C-peptide, a pro-domain that is cleaved from the mature insulin protein and thus provides evidence of the active synthesis of this hormone within the uterus Specifically, C-peptide appeared to be restricted to the endometrial epithelial cells, but underwent pronounced changes in expression levels throughout the oestrous cycle; being highly expressed at pro-oestrus and oestrus, before decreasing during metoestrus and becoming undetectable at dioestrus. The identification of insulin production in the uterus has a wide range of implications for fertility and reproduction as well as for diabetes and obesity. Our future studies will endeavor to characterise the function of insulin produced within this environment with a particular focus on its ability to influence spermatozoa.