We evaluated Retrovirus EIA kit (Roche Co.), in which virus components of three different viruses, HIV-1, HIV-2, and HTLV-I were used antigens. All the specimens from the patients with ATL, HAM, HTLV-I carrier, AIDS and AC, and from HIV-2 infected individuals were found to be positive. Four out of 40 specimens from hemophiliacs not infected with HIV-1 were found out to be positive. These specimens were confirmed to contain antibody against HTLV-I. Pseudo-negative or -positive reactions were not found in this study. Therefore, Retrovirus EIA kit should be evaluated more extensively, for the possible applications for screening of blood donors, and for selecting the sources of blood products as well as for clinical diagnoses.