Human T-lymphotrophic virus 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a disabling myelopathy, but clinical trials of specific drugs to treat it are lacking. There are many reasons for the absence of specific therapeutic studies, including difficulty in enrolling patients, inadequate measurement tools to evaluate neurologic improvement, and even lack of interest. Oral or intravenous corticosteroids are now the mainstay of HAM/TSP treatment, especially in the initial phase of the disease, when inflammation is more prominent than demyelination. Motor disability, pain, and urinary dysfunction may be ameliorated, but improvement is not sustained in many patients. Valproic acid has emerged as a potential treatment for HAM/TSP; recent evidence shows that this drug can activate viral gene expression and expose virus-infected cells to the immune system, leading to a reduction of the proviral load. Alternative drugs such as methotrexate, pentoxifylline, azathioprine, danazol, and interferon-alpha may be used if steroids fail or cannot be tolerated, but they have not been assessed in randomized clinical trials.