The invention relates to the discovery that in an animal model of Parkinson's disease (PD), administration of granulocyte colony-stimulating factor (G-CSF) to rodents having 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD restored the function of dopamine neurons. In these animals, G-CSF treatment increased the number of dopamine neurons in the substantia nigra (SN), G-CSF treatment partially restored the nigrostriatal pathway, and G-CSF restored the function of dopamine to the level before MPTP treatment. The invention also relates to the discovery that treatment of a human patient with corticobasilar ganglionic degeneration, a rare progressive neurological disorder characterized by Parkinsonism and coritcal dysfunction, with G-CSF resulted in a significant improvement in the patient's Unified Parkinson's Disease Rating Scale evaluations as well as measures of activity of daily living. The invention further relates to the discovery that G-CSF treatment of a patient who had suffered an acute stroke resulted in a significant improvement in neurological function, the patient having minimal observable disability seven years later. The methods described herein can be used to treat PD in a mammalian subject (e.g., rodent, human) as well as other neurodegenerative diseases such as Alzheimer's disease, spinal cord injury, and stroke.