Objective: Relaxin is a pleiotropic hormone of the insulin-like peptide hormone family that plays an important role in reproductive physiology as well as in fibrosis, angiogenesis, and bone remodelling. It binds to the relaxin family peptide receptors 1 and 2 (Rxfp1 and Rxfp2) and can, in addition and independently, bind and activate the glucocorticoid receptor Nr3c1. Despite the wide-ranging effect of relaxin, the expression patterns of Rxfp1 and 2 during facial development have not been examined. In this study, we aimed to identify the mRNA expression patterns of Rxfp1, Rxfp2, and Nr3c1 in oral tissues during late mouse facial development in order to pinpoint the structures that could be sensitive to relaxin signalling during this period. Design: Rxfp1, Rxfp2, and Nr3c1 mRNAs were identified by in situ hybridization using digoxigenin-labelled riboprobes on coronal sections of mouse heads from embryonic days 13.5 to 18.5. Results: We found that Rxfp1, Rxfp2, and Nr3c1 mRNAs were expressed on the developing maxilla and mandible, Meckel's cartilage, tongue, and tooth primordia between embryonic days 13.5-18.5. Conclusions: Receptors that bind relaxin were present in developing oral tissues of mice. This finding suggests that relaxin may be involved in the prenatal development of the face. (C) 2013 Elsevier Ltd. All rights reserved.