In this paper Zhigang Wei, Toni Makkai and Kiah McGregor report on 493 juveniles detained by police and interviewed as part of the Drug Use Monitoring Australia (DUMA) project. For this group of juveniles, drug use is prevalent. Three-quarters reported using at least one illicit drug at some time in their lives, 46 per cent had used two or more drugs, most frequently cannabis and amphetamines. Over half (57 per cent) had used illicit drugs in the past 30 days. The average age of initiation for cannabis use was about 13 years. Female juvenile detainees were more likely than male counterparts to test positive to heroin, amphetamines or cocaine. Few juvenile detainees (13 per cent) reported accessing treatment.