The Illicit Drug Reporting System (IDRS) is Australia’s national illicit drug monitoring system. The purpose of the IDRS is to provide a standardised, comparable approach to the monitoring of data relating to the use of heroin, cocaine, methamphetamine, cannabis and other drugs. The IDRS is a sensitive and timely indicator of drug trends both nationally and by jurisdiction. It is not intended to describe phenomena in detail, but rather, is designed to indicate the need for more detailed data collection by providing sensitive and timely data on trends in illicit drug markets. As well as drug trends, the findings highlight areas where further research is required, or where changes may need to be made in terms of education, health promotion, treatment services and policy.