In order to determine the extent to which depression complicates Huntington's disease (HD), we have analyzed the existing literature on depression in HD in order to report the prevalence, clinical manifestations, and treatment of HD depression. By means of MEDLINE literature searches and reviews of HD articles' bibliographies, we identified for our analysis 16 HD depression studies. Our results indicate that the prevalence of depression is 30% for all HD patients. Clinical manifestations of HD depression include a marked increased risk for suicide. The etiology of HD depression is unclear, but may be due to a number of factors, such as dysfunction in the caudate nucleus, dysfunction in the ventral striatum, and various genetic factors that are discussed in this review. Case reports and case series support the efficacy of standard antidepressant interventions in resolving symptoms of depression. Efficacious treatments reported in the literature include tricyclic antidepressants, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors, and electroconvulsive therapy. In this study, the successful anecdotal treatment of seven consecutive HD depressed patients with sertraline suggests that sertraline may be a safe and efficacious treatment of HD depression.