High frequency ventilation (HFV) systems have the theoretical advantage of producing less barotrauma and lung damage because of the associated smaller oscillations in alveolar pressure compared to conventional ventilators. An index of lung damage is an increase in extravascular lung water but previous studies using HFV have produced conflicting results. Lung wet-to-dry ratio, extravascular lung water and blood mass were measured in 30 rabbits divided into three groups (n = 10); spontaneously breathing (SV), conventional positive pressure ventilation (CV) and high frequency oscillatory ventilation (HFV). HFV maintained normal blood gases and produced a significant reduction in the wet-to-dry weight ratio compared to SV and CV (P less than 0.05). Extravascular lung water and blood mass were significantly reduced in HFV compared to SV (P less than 0.05). It is concluded that the system of HFV used in this study has clinical potential in the treatment of lung injury.