During the last decade, several centers have directed their research efforts at defining more efficient modalities for the accurate diagnosis of ventilator-associated pneumonia (VAP). Accurate diagnosis is an essential prerequisite for clinical investigation. Initial studies, which correlated histologic findings and quantitative bacterial cultures of the lung with the findings of protected specimen brush cultures have stimulated clinical investigation of VAF! Two diagnostic techniques, protected specimen brushing (PSB) and bronchoalveolar lavage (BAL), have been extensively investigated and have shown promising results. Advancements in the field, however, have been limited by the lack of standardization, particularly for BAL. In this communication, we attempt to standardize methodology for presently available bronchoscopic techniques and interpretation of data obtained by bronchoscopy to facilitate comparisons among investigations and to promote multicenter collaboration.