Older patients who die with Parkinson's disease (PD) have fewer pigmented neurons in the locus coeruleus and fewer substance P-containing neurons in mesopontine tegmental nuclei. We analyzed two other medullary nuclei, the dorsal vagal nucleus and the hypoglossal nucleus, in eight PD patients and six normal controls by counting neurons in serial Nissl stained sections to determine the relationship between age at death and cell loss in these nuclei. PD-related neurodegenerative changes (Lewy bodies and neuronal loss) were present only in the dorsal vagal nucleus (13,637 ± 1,323 neurons in PD, 24,885 ± 1,157 in normal controls). Cells in the intermediate rostrocaudal part of the nucleus were most severely affected. There was a significant correlation between loss of vagal neurons and age at death in PD patients. No age-related cell loss was present in the dorsal vagal nucleus of normal brains, or in the hypoglossal nucleus in either PD or normal brains. These results confirm that age-related cell death depends on whether or not there is coexistent PD.