The rostrocaudal extent of the preganglionic parasympathetics of the vagus nerve (DNV, the dorsal nucleus of the vagus, also called the dorsal motor nucleus of the vagus) was traced using the retrograde horseradish peroxidase (HRP) transport method. Labeled cells were found within, and both rostral and caudal to, the classically-defined DNV. Cell bodies of origin of the preganglionic parasympathetics of the vagus formed a continuous longitudinal, spindle-shaped column extending from an area rostral to the rostralmost border of the inferior olivary nucleus caudally through the nucleus commissuralis (NC) of the lower medulla, and continuing in an attenuated fashion in the dorsal commissural gray (CG) of the cervical spinal cord. The rostral quarter of this cell column consisted of only a few cells lateral to the fourth ventricle in the mid-medulla. The middle one-half of the DNV cell column included the classically-defined dorsal nucleus of the vagus, located dorsolateral to the hypoglossal nucleus and lateral to the fourth ventricle rostrally, and located dorsolateral to the hypoglossal nucleus and the central canal caudally. In the caudal medulla, the caudal quarter of the cell column consisted of cell bodies in the NC. Scattered labeled cell bodies were found in the CG of the spinal cord, extending caudally to the C3--C6 level.