New drug addicts in England notified to the Home Office by police force area increased from 4,587 in 1986 to 15,810 in 1996. The following other increases in new drug addicts were also noted over the same period: Wales, from 112 to 410; Scotland, from 616 to 2,030; and Northern Ireland, from 10 to 31. Figures for new drug addicts per million population increased from 96 to 323 in England, from 40 to 141 in Wales, from 120 to 401 in Scotland, and from 6 to 19 in Northern Ireland. The number of new drug addicts notified to the Home Office as addicted to heroin by police force area in England increased from 4,248 in 1986 to 13,614 in 1996. Corresponding figures were 84 to 199 for Wales, 597 to 1,334 for Scotland, and 7 to 24 for Northern Ireland. Data are also tabulated on drug addicts renotified to the Home Office and on drug addicts notified to the Home Office by Regional Health Authority (age, sex, and injecting status). 12 tables