Our study on long-term outcome of presymptomatic testing for Huntington disease had two aims: the comparison of the psychological well-being and social adjustment of carriers and non-carriers of the mutation, and the identification of psychological determinants to improve care/support of testees. We performed a cross-sectional study of 351 persons who underwent presymptomatic testing. Those who had motor signs were excluded from the comparison of asymptomatic carrier and non-carriers. A structured interview including five self-report scales and the MINI (Mini International Neuropsychiatric Inventory) was proposed to detect a psychopathology or problem with social adjustment.We interviewed 119 testees (53%), 62 non-carriers and 57 carriers after a mean delay of 3.7 years (range: 0.32 to 8.9) after their result. Depression was frequent in asymptomatic carriers (58%). Interestingly, the self reported impact of the test showed that 27% of non-carriers did not cope well with a favourable result, and a significant percentage of non-carriers (24%) were depressed during follow-up. Multivariate analysis showed that only a previous episode of depression was predictive of depression after genetic testing in both carriers and non-carriers of the HD mutation (P<0.0001).Psychological support is necessary for all testees regardless of the result of their presymptomatic test, because psychiatric care is often needed by both carriers and non-carriers.