The literature on the possible existence of a "serotonin irritation syndrome" is examined. This syndrome is an anxiety state occurring in the presence of elevated levels of atmospheric or ambient cations and is associated with elevated central and peripheral serotonin levels. Investigation of these cations' effects on microbes, insects, and mammals, including humans, shows a disruption of normal activity. It is suggested that clinicians become acquainted with the potential relationship between cation exposure and serotonin in their treatment of anxious patients. Further research exploring the etiology and diagnostic definition of this entity is urged.