This study examined the extent of heroin use in a Dublin south inner-city electoral ward, during the period 1979 to 1985. There were 82 completed questionnaires out of a possible total of 103, giving a response rate of 80%. Each of the 82 respondents had a fixed address in the area during the period, and all of them had a history of heroin use, which was validated through medical records. The extent of heroin use in the area was greatest in the 1977/81 period, and the researchers found that it was particularly marked in the under-25 age groups, especially among males aged 15 to 19 years. However, the authors found that, since 1981, there had been a marked decline in heroin use in the area.