The nucleus tractus solitarius (NTS) in the dorsal medulla is the principal visceral sensory relay nucleus in the brain. In the rat, numerous lines of evidence indicate that the caudal NTS at the level of the area postrema serves as a major integrating site for coordinating cardiorespiratory reflexes and viscerobehavioral responses. This region of the caudal NTS not only exhibits high densities of binding sites for an impressive array of transmitters and modulators but microinjections of many of these same neuroactive substances into the rat subpostremal NTS elicit pronounced cardiorespiratory and visceral response patterns. This report provides an abbreviated atlas of the rat subpostremal NTS consisting of a series of transverse, sagittal, and horizontal plates. Photomicrographs, together with their corresponding schematic drawings, are provided for the serial sections generated from each reference plane.