The main risk factor for transmission of bloodborne viruses (BBVs) in drug users in Ireland is injecting opioids, particularly heroin. Estimates from a 2014 capture-recapture study indicate that there are just under 19,000 problem opioid users in Ireland, with over 70% living in Dublin1. This is similar to the estimate from a previous capture-recapture study carried out in 20062. However, the age profile of opioid users changed significantly between 2006 and 2014. Results from the 2014 study indicate that 60% of Ireland’s opioid users are aged between 35 and 64 years compared to less than one third in the 2006 study. Furthermore, only 6% were aged between 15 and 24 years compared to over one fifth in the previous study. These results indicate a high prevalence of opioid use among older drug users, but a declining incidence of problem opioid use in Ireland.