A novel receptor family, the Mas-related G protein-coupled receptors (Mrgs, also called Sensory neuron-specific G protein-coupled receptors or SNSRs), was found in 2001. Interestingly, the mRNAs of Mrgs are expressed predominantly, if not exclusively, in non-overlapping subsets of nonpeptidergic neurons in dorsal root (DRG) and trigeminal ganglia (TG). This specific expression pattern implies significance in physiological and pharmaceutical sciences of pain processing. Study of Mrgs is a new field and will help us to understand the mechanism of pain and nociceptor development. It would also contribute to develop a new analgesic with less central side-effects. The present article summarizes the research progress about Mrgs and provides useful information, such as classification, distribution, expressing regulation and the possible functions in neural circuit and nociception.