Background: This study evaluates the importance of patient and tumor factors, receipt of preoperative radiation therapy, and American Joint Committee on Cancer stage for sphincter preservation (SP) in patients with rectal cancer. Methods: Age, sex, race, body mass index, tumor size, distance from the anal verge (DAV), differentiation, American Joint Committee on Cancer stage, and preoperative radiation were evaluated. The end point was continence versus colostomy. Comparison was done by logistic regression; data were presented as mean ± SEM; and significance was defined as P <.05. Results: Factors independently associated with SP were greater DAV, body mass index (BMI) <30, smaller tumor, and preoperative radiation therapy (all P <.05). Conclusions: DAV remains the most important factor for prediction of SP in patients with rectal cancer. Preoperative tumor size and BMI were also independent factors. Preoperative radiation therapy may increase the chance of SP in patients with large tumors, increased BMI, or low rectal tumors. © 2008 Excerpta Medica Inc. All rights reserved.