Evaluation of a new biomarker from bronchoalveolar fluid, the Clara cell protein 10, adds data to the search for a diagnostic marker for ventilator-associated pneumonia (VAP). For more than 15 years, investigators tried to identify such a marker for predicting or diagnosing VAP. Unfortunately, the results of a number of these studies are disappointing. For optimal management of critically ill, ventilated patients with clinical suspicion of VAP, clinicians need accurate microbiological information to decide to treat in case of confirmed infection and to guide the initial choice of antibiotic therapy with identification of the responsible pathogen(s). Thus, today, the potential advantages of biomarkers are to improve the rapidity and performance of current diagnostic procedures and to reduce antibiotic exposure and selective pressure.