Huntington disease (HD) is an adultonset, genetic disorder with major psychosocial implications. Although many of the psychiatric symptoms of the disorder have been attributed to the HD gene, systems factors may also account for the disorder's manifestations. Three illustrative issues--patient preselection, the denial of symptom onset, and suicide induction--are discussed from the vantage point of family systems thinking. Recently developed capacity for presymptomatic testing of HD despite the current absence of treatment or cure makes it likely that family therapists increasingly will be involved in clinical work with individuals and families in which HD occurs.