Since late 2000, anecdotal reports from drug users and health professionals have suggested that there was a reduction in the supply of heroin in Adelaide in the first half of 2001, referred to as a heroin 'drought'. The aim of this paper was to critically review evidence for this, using data obtained from 100 injecting drug users surveyed for the 2001 Illicit Drug Reporting System (IDRS). This project is carried out annually in all Australian jurisdictions, and collects up-to-date information on the markets for heroin, methamphetamine, cocaine and cannabis. This paper also investigates the possible implications of this 'drought' on patterns of drug use and drug-related harms. The 2001 IDRS found consistent reports by users of an increase in the price of heroin, together with decreases in purity and availability. These factors resulted in a decrease in the frequency of self-reported heroin use among those surveyed in 2001, and a concomitant increase in the use of other drugs, in particular methamphetamine and morphine. The heroin 'drought' appears to have had a substantial impact on several indices of drug-related harm. There was a marked decrease in the number of opioid-related fatalities, and hospital data also showed reductions in heroin-related presentations. Treatment service data showed an increase in the number of admissions related to amphetamines. There is a need for health promotion and education on the adverse effects of methamphetamine use, and the development of improved treatment protocols for methamphetamine abuse and dependence. (Review's abstract.)