Responses to extracellular nucleotides (e.g., ATP, ADP, etc.) have been demonstrated in a number of embryonic cell types suggesting they may be important signalling molecules during embryonic development. Here the authors describe for the first time the expression of a G-protein-coupled receptor for extracellular ATP, chick P2Y1 (cP2Y1), during embryonic development of the chick. During the first 10 days of embryonic development, cP2Y1 is expressed in a developmentally regulated manner in the limb buds, mesonephros, brain, somites, and facial primordia, suggesting that this receptor may have a role in the development of each of these systems.