The Illicit Drug Reporting System (IDRS) is intended to serve as a monitoring system, identifying emerging trends of local and national concern in illicit drug markets. The IDRS consists of three components: interviews with a sentinel group of people who regularly inject drugs (PWID1) conducted in the capital cities of Australia; interviews with key experts (KE), professionals who have regular contact with illicit drug users through their work; and analysis and examination of indicator data sources related to illicit drugs. Australian Drug Trends draws largely on the PWID participant survey and indicator data components of the IDRS, while KE are relied upon to provide contextual information within jurisdictions.