Mortality in young drug users in Gothenburg was studied, by following up, for about a decade, two unselected groups (ninth grade pupils and military conscripts), and selected groups of abusers from the files of the health and social welfare authorities. In the unselected groups, cannabis smoking predominated. Solvents, LSD, and central stimulants taken orally or intravenously also occurred, particularly in the selected groups. Polydrug abuse including alcohol was common, opiate abuse was rare. Observed mortality was compared with expected mortality in the same age groups. The mortality rate was significantly increased in several of the selected groups, 2.4-6.9 times in men and 1.3-7.9 times in women. Among pupils with high-frequency drug use it was increased 5.5 times in boys and not significantly increased in girls. Among pupils with low-frequency drug use it was not significantly increased in boys and increased 4.7 times in girls. Among registered pupils the mortality was increased 4.2 and 8.2 times in boys and girls respectively. Military conscripts did not display an increased mortality. The proportion of unnatural deaths was over 90%, which was significantly higher than in the population. About half of the deaths were suicides and undetermined suicides. The proportion of undetermined suicides was high among men. Two of the male deaths were homicides. In about one third of the deaths alcohol was involved. Dextropropoxyphene was present in five of the 14 intoxications among men. Although mortality was increased it is lower than in other Scandinavian studies. This may be explained by the relative youth of the abusers and the rare occurrence of opiate abuse.