A method of treating Parkinson\u27s disease in humans is disclosed, wherein glial cell-line derive neurotrophic factor (GDNF) is chronically administered directly to one or both putamen of a human in need of treatment thereof via convection-enhanced infusion using at least one implantable pump and at least one catheter. In one aspect of the present invention the GDNF is infused directly into one or both putamen through one or more indwelling intraparenchymal mutitiport brain catheters connected to one or more implantable pumps wherein the flow rate is pulsed
