BACKGROUND: The aims of this study were to assess the clinical utility of the practice of routine preoperative CT scanning and to determine its cost-effectiveness in colon cancer patients. METHODS: A 6-year database of colon cancer patients treated at a veterans affairs medical was reviewed to determine the influence of preoperative CT scanning on clinical management. Cost analysis involved comparison of the institutional cost of CT scanning with the cost savings provided by avoiding nontherapeutic operations. RESULTS: CT scans were obtained in 130 consecutive patients. CT scans provided information that was used in treatment planning in 43 (33%) patients and definitively altered the mode of treatment in 21 (16%) patients. The practice saved the institution $24,018 over 6 years. CONCLUSION: Routine preoperative CT scanning definitively alters treatment in a small number of cases and is cost-effective.