Drug Use Monitoring in Australia (DUMA) is the only project in Australia that is routinely monitoring the use of illicit drugs by people detained by police. Although there are many anecdotal stories about the use of drugs by detainees, this is the first authoritative research to both document and monitor use amongst this important group in the community. The collection began in January 1999 and the results presented here describe the extent of illicit drug use every three months in four sites across Australia. These data are comparable with international collections in a number of countries, including the United States and England. Until now, such cross-cultural comparisons have not been possible. The increase in amphetamines across all sites indicates the value of an ongoing monitoring system such as DUMA. However, the enormous differences in opiate use across the sites also suggests that a more complete monitoring system is required before we can produce a truly national figure on illicit drug use amongst detainees.