A dinucleotide repeat polymorphism in a τ intron was identified and used in a case‐control study to analyze the genetic association of τ with several neurodegenerative disease with τ pathology. Subjects with the homozygous τ AO alleles were excessively represented in the progressive supranuclear palsy (PSP) group, compared with the age‐matched healthy control group. Consequently, this allele is more frequently found in PSP than in a group of healthy subjects. This trend was not found in Alzheimer's disease or parkinsonism‐dementia complex of Guam, both of which are accompanied by major τ pathology. The result suggests τ possible involvement of τ in the pathogenesis of PSP.