We assessed prospectively clinical and quality of life changes in 9 patients with Parkinson's disease (PD; H&Y > or = 3) with severe motor fluctuations and dyskinesia who started continuous daily levodopa duodenal infusion through percutaneous endoscopic gastrostomy. Seven patients completed the follow-up period. Duration of "off" periods and time with disabling dyskinesia shortened significantly in all patients (P < 0.01). Total daily dose of levodopa infused did not differ from baseline equivalents. There were significant improvements in UPDRS-II (activities of daily living) and -IV (motor complications) in the "on" condition (P < 0.02), and in four PDQ-39 domains (mobility, activities of daily living, stigma, bodily discomfort; P < 0.05). Two patients withdrew for adverse events. Our results demonstrate that a satisfactory therapeutic window can be achieved and maintained for several months in advanced PD patients.