The invention relates to a method of diagnosis of Huntington's Disease in a diagnostic sample of a valid body tissue taken from a human subject, which comprises detecting an altered concentration of a protein in the diagnostic sample, compared with a sample of a control human subject, the protein being selected from: Swiss Prot accession number : Protein name; P10909 : Clusterin precursor; P00738 : Haptoglobin precursor; P01009 : Alpha- l-antitrypsin precursor; P01024 : Complement C3 precursor; P01620 : 1g kappa chain V-III region; P01834 : 1g kappa chain C region P01842 : 1g lambda chain C regions; P01857 : 1g gamma-1 chain C region; P01859 : Ig gamma-2 chain C region; P01876 : 1g alpha-1 chain C region P02647 : Apolipoprotein A-I precursor; P02649 : Apolipoprotein E precursor; P02652 : Apolipoprotcin A-II precursor; P02655 : Apolipoprotein C-II precursor; P02656 : Apolipoprotein C-III precursor P02671 : Fibrinogen alpha/alpha-E chain precursor; P02763 : Alpha- l-acid glycoprotein 1 precursor; P02766 : Transthyretin precursor; P02768 : Serum albumin precursor; P02787 : Serotransferrin precursor; P04196 : Histidine-rich glycoprotein precursor; P06727 : Apolipoprotein A-IV precursor; P19652 : Alpha- l-acid glycoprotein 2 precursor; P68871/P02042 : Hemoglobin beta chain/Hemoglobin delta chain; P60709 : Beta actin.