Artemin (ARTN) is a member of the glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) which regulate the development and maintenance of many neuronal populations in the mammalian nervous system. Here we report the 1.92 A crystal structure of the complex formed between ARTN and its receptor GFRalpha3, which is the initiating step in the formation of a ternary signaling complex containing the shared RET.