The Drug Use Monitoring in Australia (DUMA) project has been in operation since 1999. Over the years it has provided police, policy-makers, criminal justice practitioners and other professionals with systematic empirical data on illegal drug use among people detained and brought to a police station or watchhouse. The project currently operates at seven sites throughout Australia - Adelaide city and Elizabeth in South Australia; Bankstown and Parramatta in New South Wales; Brisbane city and Southport in Queensland; and East Perth in Western Australia. DUMA provides an independent indicator of drug-related crime within a specific area, and provides law enforcement with valuable information regarding possible shifts in trends and patterns in drug use and related criminal activity. This report presents both self-report and urinalysis data from participating detainees for the calendar year 2004. It provides an overview of the characteristics of the detainees at each site, including self-reported drug use, prior criminal behaviour and treatment history. Data are also presented on juveniles (under the age of 18) who were interviewed at the NSW sites of Parramatta and Bankstown.