101 patients with Parkinson's disease were analyzed in a retrospective study to evaluate the influence of L-Dopa monotherapy, duration of the disease and age at onset on the clinical course of the syndrome. The effects of L-Dopa dosage adjustments after hospitalization were particularly considered. RESULTS patients with late onset of symptoms showed a more accelerated deterioration as compared to those with early manifestation of the disease who also were less severely affected. Patients treated with L-Dopa for more than five years had a greater neurological deficit score than patients who had not received L-Dopa. Besides a more severe course, these patients also exhibited significantly more dyskinesias and on-off-phenomena. It should be emphasized that in our study, 73% of the 101 patients had been treated inadequately prior to admission to our clinic. The extent of neurological deficit could be improved by L-Dopa dose adjustments in those cases. Only in 11% of cases, an augmentation of the dopa medication was found to be effective in improving the clinical syndrome, whereas in 43%, a substantial reduction of dosage was necessary and resulted in a marked improvement of the clinical syndrome.