Detection of semen anti-human immunodeficiency virus (HIV) antibodies within the cervicovaginal secretions from a non-HIV-infected woman who has had a recent sexual intercourse with an HIV-infected man is theoretically possible since the seminal fluid from all HIV-infected men contains a high titer of IgG antibodies to HIV. We report the case of an HIV-seronegative African woman whose cervico-vaginal secretions contained IgG antibodies to HIV, including antibodies to HIV-env-encoded glycoproteins. This woman had also detectable prostatic specific antigens and acid phosphatase in her cervico-vaginal secretions, establishing the persistence of semen. In order to confirm whether anti-HIV antibodies in seminal fluid could be detected in vitro when mixed with cervico-vaginal secretions, 10(-1) to 10(-6) 10-fold dilutions of seminal fluid from HIV-1-seropositive donors were realized with a pool of HIV-negative cervico-vaginal secretions as diluent. Six commercial enzyme immunoassays or rapid tests were compared for semen anti-HIV detection in the secretions. At a 10(-1) dilution of the mixture, all assays were markedly positive for all tested semens and the greatest dilutions of seminal fluid showing positivity ranged from 10(-3) to 10(-5). The IgG immunocapture assay appeared to be the most sensitive test. The rapid tests permitted the detection of semen IgG antibodies to HIV at dilutions ranging from 10(-1) to 10(-3) suggesting their potential value in emergency situations.