A total of 1292 sera, provided by different USLs (Local Health Centers) in the Marche Region (Italy), was tested by ELISA and Western Blot for the detection of anti-HTLV I/II ad HIV-1 antibodies. It was decided not to follow any particular criterion when collecting the sera, so no protocol of admission was established in advance. Of the 1292 sera tested, 12 were found antibody positive to HTLV I/II, 18 to HIV-1 and 4 to both viruses. Of the seropositives, for HTLV I/II and HIV-1, respectively, 2 and 3 were prisoners; 2 and 4 were IVDAs, 3 and 7 were hematological patients, 3 and 2 were hospitalized subjects (not for hematological disorders), and 2 and 2 were positives belonging to a healthy population group. These data suggest that the viruses may also be spreading among groups other than the high-risk ones (homosexuals, IVDAs, prisoners, blood-transfusion recipients, promiscuous heterosexuals).