Monitoring plasma concentrations of antimicrobial agents used to treat infection in critically ill patients is one of the recommended strategies for improving clinical outcome. Drug monitoring has a double aim: to limit adverse events and to increase the effectiveness of the drugs. In clinical practice, however, this approach is mainly limited to monitoring plasma concentrations of vancomycin and aminoglycosides, although future extension to other antimicrobial agents would be desirable. Application of this technique varies considerably between hospitals, and this makes interpretation and comparison of the results obtained difficult. For this reason, representatives of various scientific societies related to the pharmacokinetic area have developed a series of recommendations for monitoring plasma concentrations of antimicrobials using vancomycin and several aminoglycosides as the reference. The recommendations are based on 14 questions encompassing all steps of the process: indication for the test, blood sampling (timing of blood collection, blood volume, tubes), transport to the laboratory, techniques applied, normal values, dose adjustment, and reporting the results. The purpose of these guidelines is to develop a process of monitoring plasma antimicrobial concentrations that is as homogeneous as possible to facilitate the design of multicenter studies, as well as the interpretation and comparison of results.