Abstract: The majority of people held in European prisons have severe problems associated with drug use, together with related health and social disadvantages. Those categorised as problematic drug users (PDUs) constitute a substantial proportion of prison populations in Europe. Recent figures indicate that a third to a half of prisoners having illicit drug use experience before imprisonment. Acknowledging the existence of a drug problem within prison walls often remains a taboo for prisoners, staff, management and politicians. Moreover, lack of continuity of care and support throughout the criminal justice system (CJS), from the moment of arrest to release from prison into the community, contributes to failures in reintegration, drives the “revolving door effect”, with drug users routinely caught in the criminal justice system and does not allow for the full implementation of the principle of equivalence of health services in prison comparable to those available in the community. Most of the countries, who joined the European Union (EU) most recently have, to varying degrees, im-plemented effective treatment programmes and harm reduction projects outside of the prison system. However, effective drug treatment and blood-borne virus (BBV) prevention programmes within the prison walls and follow up services for released inmates with problematic drug use still have, in most New Member States, to be developed. Overall, prison policies and practices, in particular in dealing with drug users and related (infectious) diseases, remain an important EU concern. In few of the New Member States the public health imperative of a healthy prison system receives the political attention it deserves