A retrospective study of 30 Huntington's disease families (110 patients: 75 alive and 35 dead) known to a regional genetic centre, using multiple sources of information, showed the minimum lifetime prevalence of depression to be 39% in the prodrome and the diagnosed disease phase of the illness. The frequency of symptomatic schizophrenia was found to be about 9% and significant personality changes were found in 72% of the sample, some of them leading to gross behavioural anomalies. The findings reinforce the point that depression and schizophrenia, unaccompanied or preceded by organic personality changes and/or very early neural symptoms, are unlikely to lead to the eventual manifestation of the disease.