A countrywide study conducted two years ago has put the number of known heroin users in Ireland at exactly 14,452.
The study, carried out in 2001, found 2,000 heroin users outside of Dublin and the remainder in the capital.
The research was the first of its kind carried out throughout Ireland, but a similar study in Dublin seven years ago put the number of known heroin users in the city at more than 13,000.
The latest research found that the age profile of heroin users in the capital was getting older, with the majority of users now in the 25-to-34 age group.
It also found that the level of people coming forward for treatment in Dublin had almost doubled between 1996 and 2001.