['Biofilms are complex communities of living bacteria surrounded by a protective glycocalyx. Biofilms have been implicated in the development of infections such as dental caries and hardware infections. Biofilms form on endotracheal tubes (ETT) and can impact airway resistance. The lifecycle of a biofilm has four stages. We hypothesize that there is a relationship between the stage of biofilm on the ETT and development of pneumonia.', 'Thirty-two ETT were analyzed for biofilms and staged. Staging was performed by a microbiologist blinded to all patient information. Data included development of pneumonia, duration of intubation, comorbidities, and microbiology. Pneumonia was defined as presence of fever, WBC >12 K or <4 K, infiltrate on chest X-ray, and purulent sputum with +lower airway culture (bronchoalveolar lavage or brush). Statistics were performed by a biostatistician; p < 0.05 defined significance.', 'There were 11 women and 21 men with a mean age of 50 years. Mean intensive care unit days were 13 (standard deviation ± 9.9) and mean length of intubation was 7.4 days (standard deviation ± 5.0). Half (16 of 32) the patients developed pneumonia while intubated. Eight of 10 patients with a stage IV biofilm had pneumonia. There was a relationship between increasing biofilm stage with the incidence of pneumonia (p < 0.05). Stage IV biofilms were associated with pneumonia (p < 0.02). There was no relationship to duration of intubation, patient age or hospital stay and biofilm stage.'] Is advanced endotracheal tube biofilm stage , not duration of intubation , related to pneumonia?