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. This report presents both self-report and urinalysis data from participating detainees for the calendar year 2003. 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 presented for each site on use of methylamphetamine, benzodiazepines, cannabis, cocaine, heroin, ecstasy, LSD, street methadone, self reported alcohol use, mental illness and gambling behaviour, illicit drug use and most serious offence, prior criminal behaviour and drug and alcohol treatment history, while juvenile data are also presented for Bankstown and Parramatta. During the third quarter of 2003 an addendum on amphetamines was conducted in all seven sites. Trends in recent drug use, 1999-2003, are also discussed. A 'Violence in the home' addendum was run in all sites in the first quarter of 2003. The addendum sought to determine the incidence of partner violence experienced and perpetrated by police detainees, as well as the extent of violence witnessed or experienced as a child in the home.