Now in its 6th edition, the Paxinos and Watson The Rat Brain in Stereotaxic Coordinates has been the most used reference of neuroscientists for the past twentyfive years. Both the illustrations and nomenclature of the atlas have become standard tools used by almost all research neuroscientists who deal with anatomy, physiology, or function.In 1999, the same authors published volumes Chemoarchitectonic Atlas of the Rat Forebrain and Chemoarchitectonic Atlas of the Rat Brainstem. These publications have been recognized as providing an archive of chemical markers in the rat brain guiding researchers in the identification of structures in their own preparations in many areas of research. They provided primary data which researchers could apply to their own studies. These books were based on the 4th edition of the Rat Brain in Stereotaxic Coordinates, and are now out of print.This second edition of the material in these books will combine the two volumes of the first edition into a single volume. The photographs are presented one to a page in the forebrain and midbrain areas, two to a page in the hindbrain. Different chemoarchitectonic stains are displayed with labels identifying the structures of the brain, following the delineations and nomenclature of the Rat Brain in Stereotaxic Coordinates, Sixth Edition.