Objective:To evaluate the effects of prone position ventilation combined with recruitment maneuvers(RM) on oxygenation and lung recruited volume(RV) in oleic acid-induced acute respiratory distress syndrome in canines. Methods:Twenty-four healthy canines were randomly divided into four groups after oleic acid-induced lung injury:supine position group(SC),supine position+RM group(SS),prone position group(PC) and prone position+RM group(PS). Oxygenation index and RV were measured for five hours after ARDS was reproduced. Results:(1)Compared to the SC group,oxygenation index in SS group was increased only at 2 h after onset of ARDS(P < 0.05),while that of PC and PS group improved both at 2 h and 5 h after onset of ARDS(all P < 0.05). Compared to the SC,SS,and PC group,PS group oxygenation index was much higher at 2 h and 5 h after onset of ARDS(all P < 0.05). (2)There was no significant difference of RV among the four group at 0 h after onset of ARDS(all P > 0.05). Compared to the SC group,RV in SS,PC and PS group was much higher at 2 h after onset of ARDS(all P < 0.05). At 5 h after onset of ARDS,the RV of the SS group had a tendency to decrease while the RV of the PC and PS group had a tendency to increase. Conclusion:Prone position ventilation combined with RM improved oxygenation significantly. The increase of RV may be one of the most important mechanisms of its positire effect.