The findings show that morphine use and injection is common among regular IDU in Australia. Results indicated that the rate of morphine prescription per person increased 89 percent across Australia between 1995 and 2003 for persons aged 15 to 54 years. Of the IDU surveyed in 2004, 46 percent reported illicit morphine use, particularly in areas where heroin was less available. In comparison to IDU who had not injected morphine, recent morphine injectors were more likely to be male, unemployed, out of treatment, and homeless. Recent morphine injectors were also more likely than other IDU to have injected other pharmaceutical drugs and to have reported injection-related problems. The most common injection-related harms were morphine dependence (38 percent), difficulty with veins (36 percent), and scarring or bruising (27 percent). The findings revealed that in some cases, morphine appeared to be a substitute for illicit heroin while in other cases morphine was being used to treat heroin dependence when other pharmacological treatments were unavailable. The findings also suggest that morphine injection is associated with polydrug use and with a range of problems related to the drug injection process. Data on morphine prescriptions in Australia from 1995 through 2003 were drawn from the Drug Monitoring System (DRUMS) and data on regular IDU were drawn from the Australian Illicit Drug Reporting System (IDRS) for the period 2001 through 2004. Participants of the IDRS were recruited using various methods including advertisements in newspapers, treatment centers, and needle and syringe programs. Data were analyzed using SPSS for Windows and included t-tests, odds ratio calculations, and the Mann-Whitney U-test. Future research on morphine prescriptions is required to reduce the diversion of morphine and its associated harms. Figures, tables, references