We have retrospectively investigated the antibodies against type 2 human immunodeficiency virus (Ac HIV-2) in sera from parenteral drug abusers (PDA) who had been previously investigated for HIV-1 and who fulfilled established criteria (trips, sexual contacts, etc.). Enzyme immunoassay (EIA) was positive in 7 individuals who were also carriers of HIV-1. When HIV-2 was confirmed with Western blot, in only one case a tenuous band against glycoprotein 105 (gp 105) and the remaining ones from the core was found.