During the last fifteen years the capacity of nirvanol to produce a syndrome known as "nirvanol sickness" has been widely utilized in German clinics in the treatment of violent choreas.1Nirvanol is phenyl-ethyl-hydantoin, an hypnotic resembling phenobarbital in its pharmacologic action, but with a five instead of a six membered ring nucleus. "Nirvanol sickness" consists of fever, rash and eosinophilia, coming on sharply in a high percentage of persons treated, usually from six to twelve days after the first administration of the drug. It has been generally observed that following the appearance of this syndrome the course of the disease is shortened. Recently similar reports have come from England.2Poynton and Schlesinger3have even observed the disappearance of persistent rheumatic nodules, accompanied by a lowering of temperature and quieting of the pulse rate, in four patients with "subacute rheumatism" who were given the usual course of nirvanol