Data to date indicate there has been relatively little HIV transmission through heterosexual activity compared to transmission through the sharing of drug injection equipment. This may be because the efficiency of HIV transmission through the sharing of drug equipment may be much greater than transmission through unprotected vaginal intercourse. Differences may also be due to the frequency with which a person performs acts likely to transmit the virus and the number of persons with whom those acts are practiced. Also, many of the females with whom IV drug users have sex are prostitutes, who tend to use 'safe sex' procedures. Prevention of HIV transmission from shared drug injection equipment may be critical for the control of the heterosexual transmission of HIV in New York City. Projects currently underway in New York City are expanded drug treatment programs, anti-body testing of IV users and their partners, and the education of IV users designed to reduce their high-risk practices of drug injection. 15 references.