The methamphetamine market in Australia has undergone radical changes since the late 1990s with the emergence of new more pure forms of base and ice. The current research was undertaken to fulfil a need to understand the impact of base and ice on the methamphetamine market, and the health and social consequences associated with these more pure forms of methamphetamine. The specific objectives of the research were to: i) clarify the relationship between the physical forms of methamphetamine and the terminology used to describe these different forms of the drug; ii) estimate the demand for the potent forms of base and ice methamphetamine; iii) document the nature of methamphetamine supply; iv) describe the characteristics of methamphetamine users, methamphetamine use patterns and the social and health problems associated with methamphetamine use; v) examine the relationship between methamphetamine use and criminal activity; vi) describe and estimate the prevalence of psychiatric sequelae associated with methamphetamine (i.e. psychosis and aggressive or violent behaviour); vii) examine the occupational health and safety implications of the above psychiatric sequelae for frontline workers (i.e. police, ambulance officers and emergency department staff); and to viii) determine the utility of the various methodologies employed in the project for investigating the methamphetamine market. The research used a range of different methods to understand the nature of the methamphetamine market in Sydney, including interviews with users, dealers, frontline workers, hospital records and forensic data. The results are detailed. (Executive summary, edited)