Substance abusers are an immunocompromised population, vulnerable to a wide array of new and resurgent infectious diseases - in spite of modern treatment. For example, opportunistic infections like tuberculosis are the principal cause of morbidity and mortality in HIV positive patients. Alcohol- and drug-induced disorders are wide-ranging, gaining prominence as the spectrum of emerging diseases broadens.Alcohol, Drugs of Abuse, and Immune Functions reviews the role of these immunosuppressants as cofactors in disease. It covers the basic biology and immunology of impairments to defense against infectious disease. Alcohol and drug use is consistently associated with immunosuppression, although it isn't known if it is the substance itself, a metabolite, or an indirect effect that alters disease resistance. This text explores the advances toward answering this question, examines alcohol in different settings, its relationship to important cells, and the effects it can have on vital organs such as the liver and the lungs.