Numerous studies on continuous intravenous infusion of betalactam antibiotics have indicated that this could be a useful strategy for treating nosocomial infections as well as exacerbations of pulmonary infections in patients with cystic fibrosis and episodes of febrile neutropenia. From the pharmacodynamic viewpoint, betalactam antibiotics have a time-dependent behavior. Thus, the pharmacokinetic/pharmacodynamic index that best correlates with therapeutic efficacy appears to be the time during which free antibiotic concentrations remain above the minimum inhibitory concentration (MIC) of the infecting microorganism. Continuous infusion of betalactams successfully optimizes this pharmacokinetic/ pharmacodynamic index. Furthermore, some studies have shown that this therapeutic strategy may be favorable economically.