The collection began in January 1999, and the results presented in this report describe the extent of illicit drug use every 3 months in four sites across Australia. These data are comparable with international collections in a number of countries, including the United States and England. The trend data show relatively stable patterns in recent use of cannabis and opiates over a 12-18-month period in all four sites for adult detainees; however, the data suggest that the DUMA methodology can detect changes in recent drug-use patterns in a relatively short period of time. Within a 3-month period, significant changes in recent amphetamine use were detected in one of the sites, with smaller changes observed in the other three sites. Female detainees were less likely to test positive for cannabis than their male counterparts, but they were more likely to test positive for amphetamines, cocaine, and opiates. DUMA's capacity to detect change in drug-use patterns over a relatively short period of time highlights the potential use of DUMA for strategic and policy interventions. Since the changes observed were variable between the four sites, specific local strategic and policy interventions are also vital. The different levels of use between female and male detainees require more detailed research to inform policy development and intervention strategies. 6 figures and 9 references