Objective To analyze the risk factors inducing tumor cells exfoliating during radical resection of rectal cancer. Methods Sixty patients who were diagnosed as rectal cancer from May 2006 to November 2007 and given radical operations were assigned prospectively in this study. Before cutting the rectal stump below the tumor, saline was instilled into rectum to irrigate the stump. Collected irrigating fluids were sent to pathology laboratory, and the exfoliated malignant cells were tested by HE （haematoxylin and eosin） dyeing and common smear technique. The results of examines were collected and statistical analysis, including a Logistic regression model, was performed. Results Exfoliated malignant cells were found in 27 samples. By univariate analysis, the statistically significant factors defining a high risk of exfoliating were age, tumor size, TNM stage, operation time and operation method (Plt;0.05). Only TNM stage， operation time and operation method were confirmed by Logistic regression analysis to independently result in a statistically significant increased risk of exfoliating. Conclusion Irrigating the rectal stump before cutting down the tumor is essential to avoid local recurrence. The effects of TNM stage, tumor size and operation time are important. Although the laparoscopic surgery is more predominant than conventional surgery for non-neoplasma technology, irrigating is an important process.