Pituitary adenylate cyclase-activating polypeptide (PACAP) is a polypeptide hormone related to vasoactive intestinal polypeptide (VIP). Rat PACAP receptor cDNA was isolated from a brain cDNA library by crosshybridization with rat VIP receptor cDNA. The recombinant PACAP receptor expressed in COS cells bound PACAP with about 1000 times higher affinity than VIP, and PACAP stimulated adenylate cyclase through the cloned PACAP receptor. The rat PACAP receptor consists of 495 amino acids, contains seven transmembrane segments, and has a significant similarity with other G-coupled receptors, such as VIP, glucagon, and secretin receptors. PACAP receptor mRNA was abundantly expressed in the brain, but not in the peripheral tissues except for the adrenal gland. In situ hybridization revealed a high level of expression of PACAP receptor mRNA in the hippocampal dentate gyrus, olfactory bulb, and cerebellar cortex.