Abstract： Objective To evaluate the value of modified acute physiologic and chronic health score (APACHE Ⅱ score) in predicting postoperative complications in patients with acute obstructing colorectal carcinoma. Methods Postoperative complications in 92 patients with acute obstructing colorectal carcinoma were evaluated by APACHE Ⅱ score and modified APACHE Ⅱ score (severe organ dysfunction and immune damage in chronic health indicators were replaced by the duration and degree of obstruction, which were considered as the severity of intestinal obstruction). The sensitivity,specificity, and Youden index were compared with regard to complication prediction. Receiver operating characteristic curves were plotted to calculate area under the curve (AUC). Results Twnenty-five patients developed postoperative complications including 3 deaths. The APACHE-Ⅱ score (13.72±4.24), modified APACHE Ⅱ score (19.28±4.92), intestinal obstruction severity score (5.56±2.20) were significantly higher in patients with complications than those in patients without complications (10.58±3.44,14.69±3.73,4.10±1.52,al1 P＜0.01). The sensitivity, specificity, accuracy, Youden index, and AUC were 0.640, 0.940, 0.859, 0.580, and 0.839 for the modified APACHE-Ⅱ score with 20 being the optimal cut-off point, respectively, and were 0.560, 0.896, 0.804, 0.456, and 0.784 for APACHE- Ⅱ ( 14 was the optimal cut-off point), respectively. Conclusion The modified APACHE- Ⅱ score system with the intestinal obstruction severity score is a better prediction method for the occurrence of postoperative complications in patients with acute obstructing colorectal carcinoma.