Recent data points to glutamatergic dysfunction in mood disorders, anxiety disorders, obsessive-compulsive disorder, and schizophrenia. Memantine, a drug approved by the FDA for the treatment of moderate to severe Alzheimer's disease that acts at the N-methyl-d-aspartate receptor, has been used off-label for various psychiatric disorders. Although promising, the available data for the use of memantine in these disorders is limited. Given this data, the routine use of memantine for depression, schizophrenia, obsessive-compulsive disorder, substance abuse, pervasive developmental disorders, bipolar disorder, and binge eating disorder cannot be recommended at this time.