Sebum secretion was measured on the foreheads of 47 unmedicated patients with idiopathic Parkinson's disease, aged 50-81 years and 80 healthy, matched volunteers. Sebum secretion was significantly higher in men patients aged 50-59 years than in controls; no such difference was observed in women of the same age. There was also no difference between patients and volunteers of either gender older than 60 years of age. The effects of either biperiden, L-Dopa + benserazide (a decarboxylase inhibitor) or bromocriptine treatments on sebum secretion and on 5 parkinsonian signs were evaluated over 127 days. There was a significant reduction of all measures during the treatment with the dopaminergic drugs. The only observable effect with biperiden was reduction of tremor. It is discussed whether the sebum suppressive effect of the dopaminergic drugs may be explained through their central effects.