Objective To observe the level of vascular endothelium growth factor A( VEGF-A) in exhaled breath condensate ( EBC) of patients with acute lung injury/acute respiratory distress syndrome ( ALI/ARDS) , and investigate its clinical significance. Methods EBC of 23 patients with ALI/ARDS by mechanical ventilation in intensive care unit ( ICU) were collected with improved EcoScreen condenser. EBC of 17 normal control subjects were collected with EcoScreen condensor. The level of VEGF-A was measured by ELISA in EBC and serum. The levels of VEGF-A in EBC of patients with different grades of lung injuries were compared, and the correlation was analyzed between the level of VEGF-A and clinical indicators. Results The level of VEGF-A in EBC was lower in the patients with ALI/ARDS than that of control subjects [ ( 49. 88 ±6. 32) ng/L vs. ( 56. 50 ±6. 323) ng/L, P lt;0. 01] , the level of VEGF-A was higher in the ALI patients than that of ARDS patients [ ( 53. 56 ±5. 56) ng/L vs. ( 45. 86 ±4. 45) ng/L, P lt;0. 01] ,and higher in the survival patients than that of the died patients [ ( 51. 92 ±6. 28) ng/L vs. ( 46. 05 ± 4. 58) ng/L, P lt;0. 05] . The level of VEGF-A in EBC was negatively correlated with lung injury score and A-aDO2 /PaO2 ( r = - 0. 426 and - 0. 510, respectively, P lt;0. 05) , and positively correlated with PaO2 /FiO2 and PaO2 ( r =0. 626 and 0. 655, respectively, P lt; 0. 05) . The level of VEGF-A in serum was not different between the ALI/ARDS patients and the control subjects, between the ALI and ARDS patients, or between the survival and the died patients ( all P gt;0. 05) . The level of VEGF-A in serumhad no correlation with lung injury score, A-aDO2 /PaO2 , PaO2 /FiO2 , or PaO2 ( all P gt;0. 05) . Conclusion The changes of VEGF-A in EBC of patients with ALI/ARDSmay serve as an indicator for severity and prognosis evaluation.