The following six questions are addressed: Are PNSES unrealistic and unpopular? Do PNSES conflict with the duties and principles of the prison service and its staff? Do PNSES affect levels of drug use and drug injection in prison? Would PNSES affect levels of infections? Will drug injectors use PNSES? and Will PNSES affect safety and security? The article concludes that relatively little evidence is available as a basis for assessing fully the feasibility of PNSES for the impact they can have on harm reduction within prisons. Ideological difficulties arise from the conflict of interests between the duty of prisons to control drug use and their health care duties, which include reducing the spread of infections. These ideological conflicts should be located within prison health care debates more generally. This article also discusses a number of practical considerations that surround PNSES debates. These practical problems are often considered insurmountable by those who argue against PNSES; however, in countries where the practical costs and benefits of PNSES have been considered, their impact has been found to make a positive contribution to harm reduction within prisons. PNSES ultimately constitute a political issue that is highly symbolic. The discourses that have led to drug injectors being denied a formal supply of the means to inject drugs more safely send particular signals, which, at present, show how drug injectors are viewed with little regard. 1 table and 67 references