This paper reviews the literature describing the condition of the adrenal medulla in Parkinson's disease. Parkinson's disease is a neurodegenerative disorder that is characterized primarily by the loss of dopaminergic neurons in the substantia nigra. Clinical observations have revealed that Parkinson's disease is also frequently accompanied by a variety of autonomic symptoms. The adrenal medulla is a major component of the autonomic nervous system. However, until recently this organ has not been of particular interest in Parkinson's disease. Early studies found histologic abnormalities in adrenal medullary cells, and several groups measured urinary and plasma catecholamines to determine general autonomic status. In the late 1980s adrenal medullary tissue was first transplanted to the caudate nucleus in an attempt to augment the decreased levels of dopamine, and thus treat the symptoms of Parkinson's disease. At this time the status of the adrenal medulla in this disease became clinically important. We measured the total catecholamine content of the parkinsonian adrenal medulla in tissue collected both at autopsy and in conjunction with adrenal-caudate transplants. Adrenal medullary catecholamines and several neuropeptides were severely depressed in parkinsonian glands. Thus, the adrenal medulla appears to be a target of the peripheral manifestations of Parkinson's disease.