Alcohol and illicit drug use has a significant impact on global health. Alcohol consumption is increasing worldwide, particularly in developing countries and countries in transition, leading to an increasing number of health and social problems, both acute and chronic. Illicit drug use is also increasing, particularly injection drug use, followed by an epidemic spread of HIV and other blood-borne infections. Alcohol and illicit drug use are related to key determinants of population health and are also an outcome of poor health. Globalized marketing and trade, and rapid social changes and development in the absence of strong policies and investments in public health have led to an increased availability, use and problems related to alcohol and other substance use. Public health policies and substantial investments in effective prevention and treatment approaches are needed in order to reduce the negative impact of alcohol and other drug use at national and global levels.