Parkinson's disease (PD) is a severe and progressive neurodegenerative disease. It is the second most common neurodegenerative disease, after Alzheimer's disease. It is caused by the selective loss of the dopaminergic neurons in the substantia nigra (SN) pars compacta. Although subject to intensive research, the etiology of PD is still enigmatic and treatment is basically symptomatic. Many factors are thought to operate in the mechanism of cell death of the nigrostriatal dopaminergic neurons in PD. In recent years, evidence for the role of apoptotic cell death in PD arises from morphological, as well as molecular, studies in cell cultures, animal models for PD, as well as human studies on postmortem brains from PD patients. These studies indicate that apoptosis takes place in PD and that there is a proapoptotic environment in the nigrostriatal region of parkinsonian patients. It is of utmost importance to conclusively determine the mode of cell death in PD because new "antiapoptotic" compounds may offer a means of protecting neurons from cell death and of slowing the rate of neurodegeneration and disease progression.