The increasing occurrence of antibiotic-resistant pathogens influences the treatment approach to respiratory tract infections and complicates the selection of the anti-infectious drug and dosing regimen. Pharmacokinetic (PK) and pharmacodynamic (PD) characteristics both influence dosing regimens of antimicrobials. PK (the overall disposition of the drug in the body) is reflected by the serum concentration profile over time. PD can be characterized by the susceptibility of the pathogen to the drug, determined by measuring the minimum inhibitory concentration (MIC), which is a potency of the drug. There is an increasing need to identify new therapeutic approaches which improve the chance to reduce the morbidity and obtain successful outcomes. So far, antibiotic dosing has been focused on PK concepts, mainly the penetration of drug into sites of infection and its elimination half-life. Recently, a new appealing approach integrating PK and PD features has been suggested to implement optimal antibiotic dosing regimens, since several studies in animals and humans found a striking correlation between bacteriological outcome and specific PK/PD indices. It appears it would lead to better results not only in terms of clinical and bacteriological cure but also in the whole patient care.