Alzheimer's disease (AD) is the most common form of dementia in occidental countries. Currently approved treatments for AD provide mainly symptomatic benefits without clear evidence of neuroprotection. N-methyl-D-aspartate (NMDA) receptor antagonists have therapeutic potential in several central nervous system disorders, including neuroprotective treatment in chronic neurodegenerative diseases, and symptomatic treatment in other neurologic diseases. Memantine, an NMDA antagonist, has been recently approved for the treatment of advanced AD. Due to its mechanism of action, memantine is considered a neuroprotective drug, whose utility has been demonstrated in preclinical studies. In addition, memantine is a useful symptomatic treatment for AD and vascular dementia. This paper reviews both aspects of memantine as well as some basic mechanisms mediating cognition and glutamatergic neurodegeneration.