Purine receptors are a type of plasma membrane molecules found in nearly all mammalian tissues. They are classified into three categories and include P1 receptors, P2X receptors, and P2Y receptors. They all play a key role in the variety of neuronal and non-neuronal mechanisms, which comprise pain, immune responses, exocrine and endocrine secretion, platelet aggregation, endothelial-mediated vasodilatation, and inflammation. The G protein is mainly bound to the P1 and P2Y receptors. These receptors are differentiated by considering their reactivity towards particular activators. The brain, heart, kidneys, and adipose tissue all contain P1 and P2Y receptors. These receptors are responsible for various cellular functions, comprising vascular reactivity, migration and proliferation of neural stem cells, cytokine secretion and apoptosis. The study of purine receptors is helpful for developing therapeutic strategies for those disorders, which have new action mechanisms, such as pathogenic conditions, like trauma, pain, epilepsy, ischemia, drug dependence and psychiatric disorders. The objective of this book is to present advanced studies on purine receptors as well as their pharmacological applications. Those in search of information to further their knowledge will be greatly assisted by it.