Various compounds could be considered to be vaginal microbicides, preventing heterosexual transmission of HIV (i.e. virucidal agents such as nonoxynol 9 and chlorhexidine) and antiviral agents interfering with either virus adsorption/fusion [polyanionic substances such as polysulfates (i.e. PVAS, PAVAS), polysulfonates, polycarboxylates, polyoxometalates and negatively charged albumins], or fusion/uncoating (bicyclams), or reverse transcription [dideoxynucleoside analogues, acyclic nucleoside phosphonates such as PMEA and PMPA, and non-nucleoside reverse transcriptase inhibitors (NNRTIs) such as TIBO, HEPT, and alpha-APA derivatives]. In particular, combination of two or more of these compounds seems to be an attractive approach to interrupt transmission of HIV at different stages of the infectious process.