Objective:To explore the easily applicable indicators of practical value to evaluate the prognosis of acute respiratory distress syndrome(ARDS).Methods:Blood and biochemical tests and blood-gas analyses were performed upon entry into theICUs,12 h,24 h,48 h and72 h after that in72 ARDS patients(who were admitted to theICUs of our hospital fromJanuary2000 toDecember 2009).ThenAPACHE Ⅱ scores were achieved by combining relevant physiological parameters and laboratory results.Results:There was a statistical difference between the death group and survival group at different time points upon entering theICUs in terms ofAPACHE Ⅱ score, alveolar-arterial oxygen difference and arterial blood lactate clearance rate.PaO2/FiO2values were recorded to be statistically different between the death group and survival group24 h,48 h and72 h, respectively after entry into theICUs.In addition, registered linear regression existed betweenAPACHE Ⅱ score, alveolar-arterial oxygen difference orPaO2/FiO2 value and time. APACHE Ⅱ score24 h and72 h after enteringICUs predicted mortality with an area under the ROC curve(AUC) standing respectively at0.919 and0.955.Arterial blood lactate clearance rate12 h, 24 h,48 h and72 h after enteringICUs predicted mortality with an area under theROC curve (AUC) at0.918,0.918,0.909 and0.991, respectively.Conclusions:APACHE Ⅱ score applied in combination with arterial blood lactate clearance rate is of clinical significance in assessing the prognosis ofARDS patients.