Objective To analyze the clinicopathological factors on the prognosis and investigate the necessity of adjuvant chemotherapy for patients with stage Ⅱ colorectal cancer.Methods The clinical data of 255 patients with stage Ⅱ colorectal cancer who were admitted to the First Affiliated Hospital of Sun Yat-Sen University from January 2000 to December 2005 were collected.The survival curve was drawn by Kaplan-Meier method,and the survival rate of the patients were analyzed by Log-rank test.Factors influencing the survival were analyzed by Cox regression model.Results All patients were followed up till April 23,2010,and the mean time of follow-up was (63 ± 22)months.The median survival time was 63 months.The 5-year and tumor-free survival rates were 85.3％ and 83.7％,respectively.The 5-year overall and tumor-free survival rates of patients without preoperative bowel obstruction or perforation were 86.9％ and 85.6％,which were sigaificantly higher than 72.7％and 68.4％ of patients with preoperative bowel obstruction or perforation(x2 =4.546,4.573,P ＜ 0.05 ).The 5-year overall and tumor-free survival rates of patients with negative resection margin were 85.5％ and 83.9％,which were significantly higher than 75.0％ and 75.0％ of patients with positive resection margin(x2 =7.020,6.009,P ＜ 0.05 ).The result of multivariate analysis revealed that preoperative bowel obstruction or perforation were the independent risk factors for patients with stage Ⅱ colorectal cancer(Wald =4.477,relative risk =2.371,95 ％ confidence interval:1.066-5.275,P ＜ 0.05 ).The 5-year overall and tumor-free survival rates were 87.3％ and 86.0％ for patients who received adjuvant chemotherapy,and were 82.2％ and 80.3％ for patients who did not receive adjuvant chemotherapy (P ＞ 0.05 ).Conclusions Preoperative bowel obstruction or perforation are independent risk factors for the survival of patients with stage Ⅱ colorectal cancer.Adjuvant chemotherapy could not improve the prognosis of patients with stage Ⅱ colorectal cancer.