Background: Although radical resection and postoperative chemoradiation have been the standard therapy for patients with rectal cancer, preoperative staging by local imaging and chemoradiation are widely used. We used a decision analysis to compare the two strategies for rectal cancer management. Methods: We developed a decision model to compare survival outcomes after postoperative chemoradiation versus preoperative staging and chemoradiation in patients aged 70 years with resectable rectal cancer. In the postoperative chemoradiation strategy, patients undergo radical resection and receive postoperative chemoradiation. In the preoperative staging and chemoradiation strategy, patients with locally advanced cancer receive preoperative chemoradiation and radical resection, whereas those with amenable localized tumors undergo local excision. The cohorts of patients were entered into a Markov model incorporating age-adjusted and disease-specific mortality. Outcomes were evaluated by modeling 5-year disease-specific survival for preoperative chemoradiation as less than, equal to, or greater than that of postoperative chemoradiation. Base-case probabilities were derived from published data; the Surveillance, Epidemiology, and End Results (SEER) Program database; and U.S. Life Tables. One-way and two-way sensitivity analyses were performed. The outcome measures were life expectancy and quality-adjusted life expectancy. Results: Life expectancy and quality-adjusted life expectancy were 9.72 and 8.72 years, respectively, in the postoperative chemoradiation strategy. In the preoperative staging and chemoradiation strategy, life expectancy was 9.36, 9.72, and 10.09 years and quality-adjusted life expectancy was 8.71, 9.04, and 9.37 years when 5-year disease-specific survival was less than, equal to, or greater than that of postoperative chemoradiation, respectively. The decision model was sensitive to differences in the long-term toxicity of pre- and postoperative chemoradiation. When the 5-year disease-specific survival for patients after pre- or postoperative chemoradiation was equal, the decision model was sensitive to surgical mortality and to the probability of residual lymph node disease after local excision. Conclusion: If efficacy and toxicity after pre-operative chemoradiation are equal to or better than that after postoperative chemoradiation in patients with locally advanced rectal cancer, then preoperative staging to select patients appropriate for preoperative chemoradiation is beneficial.