Up to December 2002, a total of 56, 566 and 109 cases of human T-lymphotropic virus type 1 (HTLV-I), HTLV-II and human immunodeficiency virus type 2 (HIV-2) infection, respectively, were identified in Spain. Most HTLV-I- and HIV-2-infected subjects were immigrants from endemic areas or Spaniards who had traveled to, or had sexual contacts with natives from, these areas. In contrast, HTLV-II infection was mainly limited to Spanish intravenous drug users (IDU) who were frequently coinfected with HIV-1. Among HTLV-I-infected patients, 12 developed subacute myelopathy and 4 adult T-cell leukemia. As for the HIV-2-positive subjects, only 20 (18.3%) developed AIDS. There was no evidence of an increase in the incidence of HIV-2 and HTLV-I infections over time. In contrast, HTLV-II infection has spread in recent years among the HIV-1-positive IDU population in prisons, with a rate of 18% in some regions of Spain. Nevertheless, the prevalence of HTLV-II infection in HIV-1-positive IDU outpatients is still low (4.7%).