Human T cell lymphotropic virus type-1 (HTLV-1) associated myelopathy/tropical spastic paraparesis (HAM/TSP) has been epidemiologically linked to prior blood transfusion. The prevalence of transfusion as a risk factor for infection varies among endemic areas. Here we report the relative frequency of reported history of blood transfusion among 52 patients evaluated in Sao Paulo, Brazil. A patient reported history of blood transfusion prior to the onset of symptoms, found in 15 (28.8%) of the patients, was the most important risk factor identified in this group of patients when compared with a history of sexually transmitted diseases, homo/bisexuality, sexual promiscuity (three or more sexual partners a year), and intravenous drug use. The mean time between reported transfusions and the onset of symptoms was longer than previously reported. There was no trend toward a more severe evolution to motor inability among the HAM/TSP patients with a history of previous transfusion.