Background: Carcinoembryonic antigen (CEA) is the most common marker used for diagnosis of colorectal cancer (CRC). Recent studies suggest that D-dimer (DD) can be a better tumor marker than CEA. This prospective study evaluates the value for prognosis of both markers in patients with CRC. Materials and Methods: 166 colorectal cancer patients were studied. There were 85 male patients and 81 female patients. Their mean age was 60.7±12.1 years. All had undergone surgery with curative intent for stages I and II CRC between January 2003 and December 2007. During the preoperative phase both CEA and DD were used to establish prognoses for these patients. They were monitored until relapse and/or death. Clinical pathological characteristics were evaluated and the tumor stage was determined according to the AJCC system. 5 ng/mL was determined as an abnormal value for CEA and 0.5 µg/mL as abnormal for DD. The values for both markers were determined for the recurrent cases or at the final check up of patients who survived. These studies were continued until June 2008. Results: During the preoperative phase, abnormal DD values were found in 81.3% of these patients, while abnormal values for CEA were found in 51.2%. Elevated values of DD and CEA were related to how far the cancer had advanced. Preoperative prognoses as determined by CEA and DD favor CEA as a marker for predicting both recurrence and mortality. Survival curves were similar for both markers. Conclusion: Abnormal CEA values have a higher correlation with tumor stages and have greater value for determining prognoses of relapse and mortality than does DD value elevation