The new estimates are based on and consistent with the concepts and methodology formulated by a Public Health Service task force on cost-of-illness studies (Hodgson and Meiners, 1979). The economic costs of alcohol abuse, drug abuse, and mental illness in 1980 were an estimated $190.7 billion. Alcohol abuse cost $89.5 billion; drug abuse, $46.9 billion; and mental illness, $54.2 billion. These values have changed from the 1977 values due to changes in inflation, significant methodological improvements, and population growth. Reduced productivity due to alcohol and drug abuse was estimated to cost $50.6 billion and $25.7 billion respectively. The estimate of $3.1 billion for lost productivity due to mental illness only refers to persons reporting partial work disability due to severe emotional or chronic nervous disorders. Other costs estimated involve lost employment, treatment, motor vehicle crashes, crime, and social welfare programs. 80 tables, 192 references, appended supplementary information.