In the present study, we evaluated the seroprevalence of HTLV-I/II infection among the blood donors in Santa Fe and Santiago del Estero provinces. A total of 1327 serum samples from blood donors from Rafaela blood bank of Santa Fe province and 3382 serum samples from blood donors from Dr Edgar Bouzon blood bank of Santiago del Estero province were studied. The antibody screening was done by particle agglutination assay (PA) (SERODIA, Fujirebio Inc., Tokyo, Japan) or by enzyme immuno assay (EIA) (Abbott HTLV-I/HTLV-II EIA, Abbott, Germany). The "in house" indirect immunofluorescence assay (IFA) and Western blot (Bioblot HTLV Biokit, Barcelona, Spain) were used as confirmatory assays. All the samples resulted negative for specific antibodies against HTLV-I/II. These results suggest that HTLV-I/II are not circulating in low risk populations in these provinces or that the prevalences of infection would be lower than that reported by blood banks in other provinces of Argentina.