Objective To compare the clinical value of Acute Physiology and Chronic Health Evaluation ( APACHE) Ⅱ / Ⅲ scoring system in predicting the prognosis of patients complicated with acute kidney injury ( AKI) and multiple organ dysfunction syndrome ( MODS) in ICU. Methods 318 patients with AKI and MODS treated with continuous blood purification in ICU fromJanuary 2004 to June 2010, were evaluated with APACHE Ⅱ and APACHEⅢ and analyzed retrospectively. The area under the receiveroperating characteristic curve ( AUC) and the Lemeshow-Hosmer goodness-of-fit of APACHEⅡ and Ⅲ were assessed. Results Mean scores and predicted hospital mortality of APACHEⅡ and Ⅲ were all significantly lower in the survival group than those in the non-survival group ( P lt; 0. 01) . The AUC were 0. 782 for APACHEⅡ, and 0. 755 for APACHEⅢ, with Youden’s indexes of 46. 4% and 36. 7% , respectively. Hosmer-Lemeshow test showed the calibration of the two systems was reasonable. Conclusion APACHEⅡ and Ⅲ are both good for predicting the severity and prognosis of patients complicated with AKI and MODS in ICU but APACHEⅡ is superior in clinical practice.