Protective ventilation strategies have been universally embraced because of reduced mortality. The authors tested the hypothesis that tidal volume (V_T) in an in vivo model of mechanical ventilation would modulate bactericidal function of alveolar macrophages (AMs). Adult New Zealand White rabbits were mechanically ventilated for 4 h with either a V_T of 6 ml/kg (low) or a V_T of 12 ml/kg (traditional), with each group receiving 3 cm H₂O positive end expiratory pressure (PEEP) with and without intratracheal LPS instillation (20 mg/kg). AMs were isolated from bronchoalveolar lavage fluid (BALF) taken from the whole left lung and used for bacterial killing assays. There were no significant differences in steady state levels of nitrite or AM phagocytosis and killing of Klebsiella pneumoniae, although these values trended to be slightly higher in the traditional V_T group. However, BALF protein concentrations were significantly increased in traditional V_T groups receiving LPS compared to animals ventilated with a low V_T (1407.8 ± 121.4 vs. 934.7 ± 118.2, p < 0.001). Lung wet:dry weight ratio in the traditional V_T group was increased when compared to the low V_T group without LPS, (7.3 ± 0.4 vs. 6.1 ± 0.3, respectively, p < 0.05). Additionally, IL-8 expression was significantly greater under conditions of LPS treatment and mechanical ventilation at V_T of 12 ml/kg. These results suggest that the traditional ventilator approach (12 ml/kg V_T) in a model of in vivo mechanical ventilation results in lung pathology without affecting AM antibacterial function.