Publisher Summary This chapter focuses on the clinical features and care of Huntington disease (HD). The HD gene is highly penetrant, such that clinical features emerge eventually in HD gene carriers who live long enough to manifest illness. Clinical expressivity varies, mainly related to age at clinical onset, which is heavily influenced by the extent of cytosine-adenine-guanine repeat (CAGn) expansion. The clinical characteristics of HD have traditionally been categorized as motor, cognitive, and behavioral, but these domains are highly inter-related and stem from a common process of selective neuronal degeneration and resulting gliosis and atrophy. The identification of the HD gene, the rapid pace of scientific discovery, and the expanding knowledge about the clinical and biological features of premanifest and manifest HD hold great promise for substantive therapeutic advances. The family approach to care is becoming increasingly applicable in the age of molecular genetics, and DNA predictive testing remains challenging because of often complicated and unique family dynamics and interactions. Direct prenatal DNA testing, involving detection of the actual CAG expansion in fetal cells, is accurate and also reveals the HD gene-carrier status of the at-risk parent. Reasonably effective pharmacotherapy has been developed for temporary treatment of the motor, cognitive, and behavioral symptoms of HD notwithstanding the progressive underlying neurodegeneration. The chapter also discusses the treatment of movement disorder, experimental treatments for HD, and restorative strategies.