Human T cell lymphotropic virus type1(HTLV-1)causes HTLV-l-associated myelopathy/tropical spastic paraparesis (HAM/TSP). We used interferon- enzyme-linked immunospot assays with overlapping peptides spanning the entire HTLV-1proteome to test whether the HTLV-l-specific CD8+ cells differed significantly in frequency or immunodominance hierarchy between patients with HAM/TSP and asymptomatic carriers and whether the frequency correlated with provirus load. Tax was the immunodominant target antigen. There was no significant qualitative or quantitative difference in the HTLV-l-specific CD8+ cell response between the 2 groups. Virus-specific CD8+ cell frequency alone does not indicate the effectiveness of the cytotoxic lymphocyte response in controlling provirus load at equilibrium.