Drug abuse is a growing problem in industrialized countries, opening the way to new diseases of the respiratory tract. It has been demonstrated that regular inhalation of cannabis has the same consequences as tobacco smoking. The same cannot be said for other drugs. Cocaine, amphetamines or crack expose the patient to particular toxic effects: in addition to barotrauma related to the administration route, syndromes of acute respiratory distress have been described. These result either from bronchial reactions, asthma exacerbation or eosinophil bronchopneumonia, or alveolar involvement: intra-alveolar bleeding, pulmonary edema or organized pneumonia. Respiratory complications induced by opiates, often used in injections, are related to central alveolar hypoventilation and/or the development of injury from pulmonary edema or pneumonia. The pathophysiology of these lesions is not perfectly understood. Besides these specific conditions, infection is a major problem in drug abusers, irrespective of the drug: bacterial pneumonia, tuberculosis, HIV infection are much more frequent in this high-risk group. Finally repeated intravenous injections of various drugs designed for oral intake can lead to severe complications such as pulmonary hypertension or toxic interstitial lung disease. Summarizing, respiratory diseases in drug abuses can take on a wide range of quite complex presentations. Occasional or regular use of illicit drugs can lead, not exceptionally, to severe respiratory complications requiring rapid management. Knowledge of the principal complications and the appropriate diagnostic procedures is indispensable.