Following on from last edition's Harm Reduction Digest on drug consumption facilities this Digest investigates what can be learnt from the Swiss and Dutch trials of heroin prescribing about the unintended consequences of this controversial intervention to reduce heroin-related harm. The authors of the paper bring considerable experience in the implementation and evaluation of such schemes in Europe and their consideration in Australia. The paper systematically addresses concerns about heroin prescribing and suggests further research to respond to some unanswered questions.