Spreading depression (SD) resembles a concerted, massive neuronal/glial depolarization propagating within the gray matter. Being associated with cerebropathology such as cerebral ischemia or hemorrhage, epileptic seizures, and migraine, it is well studied in cortex and hippocampus. We have now analyzed the susceptibility of rat brainstem to hypoxia-induced spreading depression-like depolarization (HSD), which could critically interfere with cardio-respiratory control. In rat brainstem slices severe hypoxia (oxygen withdrawal) triggered HSD within minutes. The sudden extracellular DC potential shift of approximately -20 mV showed the typical profile known from other brain regions and was accompanied by an intrinsic optical signal (IOS). Spatiotemporal IOS analysis revealed that in infant brainstem, HSD was preferably ignited within the spinal trigeminal nucleus and then mostly spread out medially invading the hypoglossal nucleus, the nucleus of the solitary tract (NTS), and the ventral respiratory group (VRG). The neuronal hypoxic depolarizations underlying the generation of HSD were massive, but incomplete. Also the propagation velocity of HSD and the associated extracellular K+ rise were less marked than in other brain regions. In adult brainstem, HSD was mostly confined to the NTS, and its occurrence was facilitated by hypotonic solutions, but not by glial poisoning or block of GABAergic and glycinergic synapses. In conclusion, brainstem tissue reliably generates propagating HSD episodes, which may be of interest for basilar-type migraine and brainstem infarcts. The preferred occurrence of HSD in the infant brainstem and its propagation into the VRG may be of importance for neonatal brainstem pathology such as sudden infant death syndrome.