Parkinson's disease is a progressive disease with selective dopaminergic neuronal loss. The pathophysiology is at present better understood with plurifactorial etiology, including genetic predisposition and environmental toxic factors. The mechanisms of cell death are based upon oxidative stress and apoptosis. The heterogeneity of dopaminergic neuronal loss leads to etiopathogenic clues. In the same way, the model of functional organization of basal ganglia circuitry gives a basis for further experimental and therapeutic research.