Memantine, a non-competitive NMDA receptor antagonist approved for Alzheimer's disease with a good safety profile, is increasingly being studied in a variety of non-dementia psychiatric disorders. We aimed to critically review relevant literature on the use of the drug in such disorders. We performed a PubMed search of the effects of memantine in animal models of psychiatric disorders and its effects in human studies of specific psychiatric disorders. The bulk of the data relates to the effects of memantine in major depressive disorder and schizophrenia, although more recent studies have provided data on the use of the drug in bipolar disorder as an add-on. Despite interesting preclinical data, results in major depression are not encouraging. Animal studies investigating the possible usefulness of memantine in schizophrenia are controversial; however, interesting findings were obtained in open studies of schizophrenia, but negative placebo-controlled, double-blind studies cast doubt on their validity. The effects of memantine in anxiety disorders have been poorly investigated, but data indicate that the use of the drug in obsessive-compulsive disorder and post-traumatic stress disorder holds promise, while findings relating to generalized anxiety disorder are rather disappointing. Results in eating disorders, catatonia, impulse control disorders (pathological gambling), substance and alcohol abuse/dependence, and attention-deficit hyperactivity disorder are inconclusive. In most psychiatric non-Alzheimer's disease conditions, the clinical data fail to support the usefulness of memantine as monotherapy or add-on treatment However, recent preclinical and clinical findings suggest that add-on memantine may show antimanic and mood-stabilizing effects in treatment-resistant bipolar disorder.