DESPITE a considerable amount of research the locus of the essential pathological lesion of Parkinsonism remains in doubt. The neostriatum and the substantia nigra are favoured sites, but lesions have been described in many other regions of the nervous system, including the medulla oblongata. However, there does not appear to be unanimity of opinion concerning medullary abnormalities in Parkinsonism. Because of this, and because lesions of the medulla could explain some of the autonomic manifestations of Parkinsonism, it was determined to investigate the pathology of this region, with particular reference to the dorsal vagal nucleus, the hypoglossal nucleus and the nucleus ambiguus. The result of this study is now reported.