Current drug abusers in Norway seem to differ from those of 25-30 years ago in several respects, namely with regard to selection to drug abuse, living conditions, and the social responses to drug abuse. These factors may all be relevant for morbidity and mortality. Mortality and excess mortality under the age of 50 was assessed on the basis of data on 1,491 drug abusers admitted to the National Clinic for Drug Abusers (Statens klinikk for narkomane) during the years 1961-91. A significant excess mortality among the drug abusers was found for both genders, in all age groups and for all three decades. Males displayed a higher mortality than females, and the mortality among drug abusers increased with increasing age. Excess mortality was higher for women than for men and decreased with increasing age. The most prevalent causes of death were overdoses, suicides and accidents. Mortality from overdoses and diseases was higher among persons admitted during the 1970s and 1980s compared with persons admitted during the 1960s. The results are discussed in light of the qualitative differences between the former and present populations of drug abusers in Norway.