While this term literally means “not sitting,” and was originally applied to an impaired ability to sit down or sit still, it is now applied primarily to restlessness and jitteriness occasionally produced by tranquilizers of the pheno- thiazine type (Compazine, Trilafon, Stelazine). As Kalinowsky (1958) points out, the reaction is sometimes so intense that it becomes “impossible for the patients to sit still day or night, and is described by them as more difficult to endure than any of the symptoms for which they had been originally treated.” The restlessness usually disappears, however, when the dosage is lowered. The term is still used by some psychiatrists in the original sense. In the psychological form of acathisia, the patient experiences acute anxiety whenever he sits down or thinks of sitting down. One psychotic patient believed the world would be destroyed if he sat down. In such cases sitting has a symbolic meaning which frequently remains obscure. An organic form of acathisia is also found in certain brain diseases which affect the striopallidal area (the basal ganglia deep within the cerebral hemispheres). Some of these patients cannot sit still, or do so only with an effort. They must get up, or move about, or shift the position of their limbs because inaction is unbearable. Typically, they rock back and forth incessantly, pace the floor, or kick in bicycling fashion while in bed. These reactions are accompanied by anxiety, irritability, and insomnia.