This work aims to contribute to the evidence base regarding the health of those who experience homelessness in Ireland by collating data on methadone use, drug-related deaths and emergency department presentations due to self-harm. Data from the Central Methadone Treatment List (CTL), National Self-Harm Registry Ireland and the National Drug-Related Deaths Index were analysed. The percentage on the CTL registered as being of no fixed abode (NFA) or homeless increased from 2% to 7% from 2011-2014. The absolute number of presentations with deliberate self-harm from those of NFA increased by 49% from 2007-2014. The number of drug-related deaths amongst those of NFA or homeless and who died in Dublin fluctuated from 2004-13 with an overall upward trend. There is an urgent need to adequately resource and coordinate those services which aim to address factors (social and health inequalities, mental ill-health and addiction) which lead people into - and prevent them exiting from - homelessness.