Pulmonary infections are common and caused by a wide range of viruses, bacteria, parasites and fungi. They consist of lower respiratory tract infections with community and hospital acquired acute pneumonia, bronchitis, lung abscess, fungal infections and tuberculosis. The management of these infections should be based on guidelines that take into account the microorganisms most frequently involved as a basis for empirical treatment, with identification of causative microorganisms allowing targeted treatments. The patient's immune status, physiological changes leading to changes in pharmacokinetics, and the characteristics of drugs may result in a microbiological and/or clinical failure when using standard doses. Knowledge of these elements is essential for optimal management. The goal of therapeutic drug monitoring is to use drug concentrations and pharmacokinetic/pharmacodynamic objectives to manage a patient's medication regimen, optimize outcome and prevent resistance or toxicity. To make the best use of the resources, it is not possible to carry out systematic therapeutic drug monitoring. We need to define drugs and patients where there is most likely to be benefit from therapeutic drug monitoring. This must be a part of a comprehensive approach to patient care. (C) 2017 SPLF. Published by Elsevier Masson SAS. All rights reserved.