There is currently considerable interest in the possibility of developing a potent, nontoxic anti-HIV agent that could be used intravaginally to reduce the risks of transmission of HIV. Worldwide up to 80% of HIV infections have been acquired heterosexually. Projections suggest that by the year 2000 approx 25 million individuals worldwide will have been infected by heterosexual transmission. This spread of infection is particularly rapid in parts of Africa, Asia, and Latin America. In the absence of a prophylactic vaccine, there is an urgent need to develop safe, effective, female-controlled, topical virucidal preparations to prevent sexual transmission of HIV and other sexually transmitted diseases (STDs). Many assays directed against the virus have had problems with removal of the presumptive agents, which in many cases are toxic to the cell culture system. Methods have includes dilution, centrifugation, and erythrocyte ghost preparations, but these have problems with virus dilution and an inability to examine the kinetics of inactivation.