OBJECTIVE To investigate the protective efficacy of propofol against paraquat induced lung injury. METHODS One hundred and twenty-eight male Wistar rats were randomizedly divided into three groups: the control group (n = 8), the intoxication group (n = 60) and the propofol group (n = 60). One hundred and twenty rats were once administered with 5 mg/kg paraquat (PQ) by the intragastrical injection to establish the model of PQ induced lung injury. The propofol of 10 mg/kg was administered intraperitoneally in the propofol group (60 rats) twice a day for four consecutive days one hour after the rats were intoxicated while the normal saline of the same amount as propofol in the propofol group was administered in the intoxication group (60 rats) one hour after the rats were intoxicated. The intragastrical injection of 1 mg/kg normal saline was administered once in the control group (8 rats). On the first, the third, the seventh, the 14th and the 28th day after treating, the level of malondialdehyde (MDA) in plasma, bronchoalveolar lavage fluid (BALF) and lung homogenate, and the content of hydroxyproline (HPY) in lung homogenate, the cell count of BALF were detected. Meanwhile, pathological changes of lung were examined under optical microscope. RESULTS The level of MDA in plasma on the first, the third and the seventh day and in BALF and lung homogenate on the first and the third day in the propofol group [in plasma: (4.31 +/- 0.94), (4.04 +/- 0.87) and (3.24 +/- 1.14) nmol/ml; in BALF: (3.47 +/- 1.09) and (2.79 +/- 1.11) nmol/ml; in lung homogenate: (7.54 +/- 0.63) and (8.41 +/- 1.23) nmol/ml] were significantly lower than those in the intoxication group [in plasma: (10.15 +/- 3.15), (6.97 +/- 1.6 5) and (5.44 +/- 0.66) nmol/ml; in BALF: (5.58 +/- 1.19) and (4.86 +/- 1.89) nmol/ml; in lung homogenate: (10.20 +/- 2.43) and (10.71 +/- 171) nmol/ml, P < 0.05 or P < 0.01]. The total cell count of BALF on the first, the third and the seventh day after intoxication in the propofol group was significantly less than that in the intoxication group respectively (P < 0.05). The histological changes such as alveolar edema, hemorrhage and inflammatory cell infiltration in the propofol group were less than those in the PQ group. CONCLUSIONS Propofol could reduce the level of MDA and relieve paraquat induced lung injury.