... In contrast to parts of Europe and the Americas, there has been limited research as to whether drug use plays a significant role in the spread of HIV infection in Africa. Research has shown that heavy use of alcohol is related to sexual risks for HIV transmission in South Africa, but the nature of the association is not well understood (Morojele, Kachienga, Nkoko, Moshia, Mokoko, Parry, Nkowane & Saxena, 2004;Morojele, Kachienga, Mokoko, Nkoko, Parry, Nkowane, Moshia & Saxena, in press;Simbayi, Kalichman, Jooste, Mathiti, Cain & Cherry, 2004). There is also evidence that cannabis use, the most commonly used non-alcoholic substance in South Africa (Parry, Pluddemann, Donson, Sukhai, Marais & Lombard, 2005), is related to sexual risk behaviors (Flisher, Parry, Evans, Muller & Lombard, 2003). ...