What is a comprehensive drug treatment system and why do we also need drug free treatment in prisons? Taking as an example in-prison Therapeutic Communities (TC) in the Republic of Moldova and Romania, experts and prison managers from France, Germany, Norway, Moldova, Romania and the United Kingdom discussed at the Pompidou Group Symposium, held on 20 September 2019, how TCs can be embedded in a wider system of health services for drug dependent people who are incarcerated. It was recommended to closely monitor the Romanian and Moldovan achievements and to support other countries to in establishing their own in-prison TCs. The Symposium was part of the conference of the European Federation of Therapeutic Communities that took place in Thessaloniki from 18th to 20th September 2019, and showcased the introduction of the first in-prison TC in the Republic of Moldova supported by the Pompidou Group’s Criminal Justice and Prison Programme.