Predictive testing for Huntington disease is now possible by using DNA markers close to the mutant gene. Such tests result in an increased or decreased risk estimate as to whether the person tested has inherited the mutant gene. Persons who already manifest subtle signs of the disease but see themselves as presymptomatic will also present to the preclinical testing programs. The authors report a severe psychiatric reaction to a positive clinical diagnosis of Huntington disease in a woman enrolled in a pilot preclinical program who had a history of psychiatric illness and hospitalizations. She is the only one of 60 persons currently enrolled in the program who has had a serious crisis. The authors demonstrate the need for readily available and ongoing counseling services for all persons participating in such a program.