Objective(s): The aim of this study was to investigate the association between HLA class I alleles (HLA-A*02, HLA-A*24, HLA-Cw*08, HLA-B5401) and proviral load in HTLV-I associated myelopathy/tropical spastic paraperesis (HAM/TSP) patients in Iranian population. This evidence concerns the gene HLA-A and tropical spastic paraparesis.