This paper aims to provide surveillance information about the extent and consequences of alcohol and other drug (AOD) use by adolescents for three sentinel sites in South Africa (Cape Town, Durban and Gauteng province). From 1997 to 2001, data were gathered from multiple sources, including specialist treatment centres, trauma units, school students, rave party attenders, and arrestees. Since the start of surveillance, an increasing proportion of South African adolescents are using AODs. Surveys point to high levels of alcohol misuse among high school students, with alcohol being the most common substance of abuse. Cannabis is the most frequently reported illicit drug of abuse among adolescents. This is reflected in the large proportion of adolescents receiving treatment for cannabis, cannabis-positive arrestees, and cannabis-positive trauma patients. Cannabis smoked together with methaqualone is the second most common primary drug of abuse in Cape Town. Arrestee data highlights the potentially negative effect of adolescent methaqualone use. Cocaine and heroin are emerging as problem drugs of abuse among adolescents in large metropolitan centres. Ecstasy (MDMA) use occurs mainly among adolescents who attend rave parties and clubs. The study points to the need for AOD intervention programmes that target young people and the need for continued monitoring of adolescent AOD use in the future.