The evolution of symptoms and therapeutic response in a group of have been followed parkinsonian patients 81 for a period of 4 years. Hoehn and Yahr, and Webster's scales have been used. In addition CT scan, EEG, ECG, blood and urine analyses have been carried out. Treatment was carried out with L-Dopa and decarboxylase inhibitor (benserazide for 50% of cases and carbidopa for the other 50%). Anticholinergics (esp. metixene) were often required. The initial response was satisfactory for all patients except one who had hydrocephalus (with normal pressure). Four years later, the initial improvement diminished by about 1/3. Side effects occurred in 80.24% of cases in the beginning, and in 82.50% of cases after 4 years. Dyskinesias, confusional state and "on-off" phenomenon increased with time, whereas gastric trouble diminished. CT scan were obtained in all patients and atrophic changes were found in 82.7%. There were no correlations between localization and severity of anatomical lesions on the one hand, and therapeutic response and side-effects on the other. It is suggested that the severity of the disease depends mainly on the degree of neurochemical integrity in the affected area rather then to the extent of anatomical lesions.