1. Relaxin is an extracellular matrix (ECM)-remodelling hormone that is functionally important in reproductive tissues, brain, lung and heart. 2. Recently, the human relaxin receptor was identified as leucine-rich repeat-containing G-protein-coupled receptor 7 (LGR7). 3. Using human LGR7 as a template, we identified mouse and rat LGR7 orthologues in the Celera and National Centre for Biotechnology Information databases. 4. At the protein level, mouse and rat LGR7 share 85.2 and 85.7% identity with human LGR7, respectively. 5. Mouse LGR7 mRNA was detected in all tissues where relaxin binding is observed. 6. Mouse and rat LGR7 bound [33P]-relaxin with high affinity and, upon relaxin treatment, both receptors stimulated cAMP production in transfected HEK 293T cells. 7. These results indicate that mouse and rat LGR7 are the relaxin receptors in these species. 8. The actions of relaxin in rodents are well characterized, providing an established platform for research into the molecular pharmacology of the highly conserved relaxin receptor.