The World Health Organization (WHO) international meeting on prisons and health, held in Lisbon, Portugal, on 11–12 December 2017, brought together more than 100 experts in the field of prison and public health from 30 countries worldwide. This document outlines their proposed conclusions, for wider dissemination to all those who could improve the current position worldwide with respect to drugs and drug-related harms in prison, which continue to challenge prison systems and the wider community.