The palmomental reflex (PMR), obtained by mechanical stimulation of the skin of the thenar and hypothenar eminences of the hand and recording the surface EMG response from the chin muscles homolateral and contralateral to the side of stimulation, was studied in normal subjects and in a group of akinetic parkinsonians, both de novo and treated. PMR was present in most subjects of both groups. No differences regarding the incidence of the PMR homolateral to stimulation of the thenar eminence was found between controls and patients, and it was non-habituating in both groups. When the hypothenar eminence was stimulated, the PMR was present in about half of the subjects of both groups. PMR was present contralaterally in both normal and patients, whereas bilateral PMR prevailed in parkinsonians. Latency and duration of the reflex were significantly shorter in parkinsonians than in controls. The data are discussed in the light of the pathophysiology of the PMR putative pathways in normal subjects and in Parkinson's disease.