In this study, HTLV-1 PVL was decreased in HLA-A*24-positive HAM/TSP patients compared to negative patients, while the allele frequency of HLA-A*24, which presents Tax 301–309, an immunodominant epitope for CTLs, was increased in HAM/TSP patients compared to ACs. This evidence concerns the gene HLA-A and tropical spastic paraparesis.