The presence of antibodies against human immunodeficiency virus type 2 (HIV-2) was retrospectively investigated in serum samples from 433 parenteral drug abusers from Barcelona. A third generation ELISA was used for the initial screening of sera, and a specific western blot technique for the definitive confirmation of the results. The presence of anti-HIV-2 was demonstrated in 9 samples (prevalence 2.1%). All of them belonged to patients also infected with HIV-1. The 9 cases reported here are the first seropositive patients for HIV-2 described in native individuals from this country.