An array of intellectual, practical and political challenges will be faced both if the Australian Capital Territory "heroin trial" does or does not eventuate. The intellectual challenges include the development of new methodologies and analytical tools for some of the outcome measures; the further development of a research process which involves all the relevant disciplines and interest groups; and capitalizing on an unprecedented opportunity to investigate the pharmacokinetics of heroin. The practicalities of setting up a trial also present a number of challenges, as does incorporating a health development approach. Political challenges include getting a sensible decision made about the trial, avoiding capture of the debate by supporters or opponents of drug law reform and avoiding unrealistic expectations. The major challenge if the trial does not go ahead is to implement other well-considered proposals which can be carefully evaluated.