Obsessive compulsive disorder (OCD) can often be effectively treated with cognitive behavioral therapy or serotonin reuptake inhibitors. About one-third of patients, however, do not receive adequate symptom relief. Jon E. Grant discusses the potential of monoamine oxidase inhibitors (MAOIs) in treatment-resistant OCD. In an article in the journal, Dr. Grant and his coauthors present new data from a case series of nine patients; three had marked improvement on phenelzine and three had some improvement. Large-scale trials are needed to fully assess the benefits and risks of the therapy in this population group.